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<A HREF="#toc">Table of Contents</A><P>
<H2><A NAME="sect0" HREF="#toc0">Name</A></H2>
vector - Vector data type for Tcl
<H2><A NAME="sect1" HREF="#toc1">Synopsis</A></H2>
<B>vector
create <I>vecName </I></B>?<I>vecName</I>...? ?<I>switches</I>? <P>
<B>vector destroy <I>vecName </I></B>?<I>vecName</I>...? <P>
<B>vector
expr <I>expression</I></B> <P>
<B>vector names </B>?<I>pattern</I>...?
<H2><A NAME="sect2" HREF="#toc2">Description</A></H2>
The <B>vector</B> command creates
a vector of floating point values. The vector's components can be manipulated
in three ways: through a Tcl array variable, a Tcl command, or the C API.
<H2><A NAME="sect3" HREF="#toc3">Introduction</A></H2>
A vector is simply an ordered set of numbers. The components
of a vector are real numbers, indexed by counting numbers. <P>
Vectors are common
data structures for many applications. For example, a graph may use two
vectors to represent the X-Y coordinates of the data plotted. The graph
will automatically be redrawn when the vectors are updated or changed. By
using vectors, you can separate data analysis from the graph widget. This
makes it easier, for example, to add data transformations, such as splines.
It's possible to plot the same data to in multiple graphs, where each graph
presents a different view or scale of the data. <P>
You could try to use Tcl's
associative arrays as vectors. Tcl arrays are easy to use. You can access
individual elements randomly by specifying the index, or the set the entire
array by providing a list of index and value pairs for each element. The
disadvantages of associative arrays as vectors lie in the fact they are
implemented as hash tables.
<UL>
·<LI>There's no implied ordering to the associative
arrays. If you used vectors for plotting, you would want to insure the
second component comes after the first, an so on. This isn't possible since
arrays are actually hash tables. For example, you can't get a range of values
between two indices. Nor can you sort an array. </LI>·<LI>Arrays consume lots of memory
when the number of elements becomes large (tens of thousands). This is
because each element's index and value are stored as strings in the hash
table. </LI>·<LI>The C programming interface is unwieldy. Normally with vectors, you
would like to view the Tcl array as you do a C array, as an array of floats
or doubles. But with hash tables, you must convert both the index and value
to and from decimal strings, just to access an element in the array. This
makes it cumbersome to perform operations on the array as a whole. </LI>
</UL>
<P>
The <B>vector</B>
command tries to overcome these disadvantages while still retaining the
ease of use of Tcl arrays. The <B>vector</B> command creates both a new Tcl command
and associate array which are linked to the vector components. You can
randomly access vector components though the elements of array. Not have
all indices are generated for the array, so printing the array (using the
<B>parray</B> procedure) does not print out all the component values. You can
use the Tcl command to access the array as a whole. You can copy, append,
or sort vector using its command. If you need greater performance, or customized
behavior, you can write your own C code to manage vectors.
<H2><A NAME="sect4" HREF="#toc4">Example</A></H2>
You create
vectors using the <B>vector</B> command and its <B>create</B> operation. <BR>
<CODE># Create a new vector. <BR>
vector create y(50)<BR>
</CODE><P>This creates a new vector named <I>y</I>. It has fifty components, by default,
initialized to <I>0.0</I>. In addition, both a Tcl command and array variable,
both named <I>y</I>, are created. You can use either the command or variable to
query or modify components of the vector. <BR>
<CODE># Set the first value. <BR>
set y(0) 9.25<BR>
puts "y has [y length] components"<BR>
</CODE><P>The array <I>y</I> can be used to read or set individual components of the vector.
Vector components are indexed from zero. The array index must be a number
less than the number of components. For example, it's an error if you try
to set the 51st element of <I>y</I>. <BR>
<CODE># This is an error. The vector only has 50 components.<BR>
set y(50) 0.02<BR>
</CODE><P>You can also specify a range of indices using a colon (:) to separate the
first and last indices of the range. <BR>
<CODE># Set the first six components of y <BR>
set y(0:5) 25.2<BR>
</CODE><P>If you don't include an index, then it will default to the first and/or
last component of the vector. <BR>
<CODE># Print out all the components of y <BR>
puts "y = $y(:)"<BR>
</CODE><P>There are special non-numeric indices. The index <I>end</I>, specifies the last
component of the vector. It's an error to use this index if the vector is
empty (length is zero). The index <I>++end</I> can be used to extend the vector
by one component and initialize it to a specific value. You can't read
from the array using this index, though. <BR>
<CODE># Extend the vector by one component.<BR>
set y(++end) 0.02<BR>
</CODE><P>The other special indices are <I>min</I> and <I>max</I>. They return the current smallest
and largest components of the vector. <BR>
<CODE># Print the bounds of the vector<BR>
puts "min=$y(min) max=$y(max)"<BR>
</CODE><P>To delete components from a vector, simply unset the corresponding array
element. In the following example, the first component of <I>y</I> is deleted.
All the remaining components of <I>y</I> will be moved down by one index as the
length of the vector is reduced by one. <BR>
<CODE># Delete the first component<BR>
unset y(0)<BR>
puts "new first element is $y(0)"<BR>
</CODE><P>The vector's Tcl command can also be used to query or set the vector. <BR>
<CODE># Create and set the components of a new vector<BR>
vector create x<BR>
x set { 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 }<BR>
</CODE><P>Here we've created a vector <I>x</I> without a initial length specification. In
this case, the length is zero. The <B>set</B> operation resets the vector, extending
it and setting values for each new component. <P>
There are several operations
for vectors. The <B>range</B> operation lists the components of a vector between
two indices. <BR>
<CODE># List the components <BR>
puts "x = [x range 0 end]"<BR>
</CODE><P>You can search for a particular value using the <B>search</B> operation. It returns
a list of indices of the components with the same value. If no component
has the same value, it returns <I>""</I>. <BR>
<CODE># Find the index of the biggest component<BR>
set indices [x search $x(max)]<BR>
</CODE><P>Other operations copy, append, or sort vectors. You can append vectors
or new values onto an existing vector with the <B>append</B> operation. <BR>
<CODE># Append assorted vectors and values to x<BR>
x append x2 x3 { 2.3 4.5 } x4<BR>
</CODE><P>The <B>sort</B> operation sorts the vector. If any additional vectors are specified,
they are rearranged in the same order as the vector. For example, you could
use it to sort data points represented by x and y vectors. <BR>
<CODE># Sort the data points<BR>
x sort y<BR>
</CODE><P>The vector <I>x</I> is sorted while the components of <I>y</I> are rearranged so that
the original x,y coordinate pairs are retained. <P>
The <B>expr</B> operation lets
you perform arithmetic on vectors. The result is stored in the vector.
<BR>
<CODE># Add the two vectors and a scalar<BR>
x expr { x + y }<BR>
x expr { x * 2 }<BR>
</CODE><P>When a vector is modified, resized, or deleted, it may trigger call-backs
to notify the clients of the vector. For example, when a vector used in
the <B>graph</B> widget is updated, the vector automatically notifies the widget
that it has changed. The graph can then redrawn itself at the next idle
point. By default, the notification occurs when Tk is next idle. This way
you can modify the vector many times without incurring the penalty of the
graph redrawing itself for each change. You can change this behavior using
the <B>notify</B> operation. <BR>
<CODE># Make vector x notify after every change<BR>
x notify always<BR>
<tt> </tt> <tt> </tt> ...<BR>
# Never notify<BR>
x notify never<BR>
<tt> </tt> <tt> </tt> ...<BR>
# Force notification now<BR>
x notify now<BR>
</CODE><P>To delete a vector, use the <B>vector delete</B> command. Both the vector and
its corresponding Tcl command are destroyed. <BR>
<CODE># Remove vector x<BR>
vector destroy x<BR>
<H2><A NAME="sect5" HREF="#toc5"></CODE><P>Syntax</A></H2>
Vectors are created using the <B>vector create</B> operation. Th <B>create</B>
operation can be invoked in one of three forms:
<DL>
<DT><B>vector create <I>vecName</I></B> </DT>
<DD>This
creates a new vector <I>vecName</I> which initially has no components. </DD>
<DT><B>vector create
<I>vecName</I></B>(<I>size</I>) </DT>
<DD>This second form creates a new vector which will contain
<I>size</I> number of components. The components will be indexed starting from
zero (0). The default value for the components is <I>0.0</I>. </DD>
<DT><B>vector create <I>vecName</I></B>(<I>first</I>:<I>last</I>)
</DT>
<DD>The last form creates a new vector of indexed <I>first</I> through <I>last</I>. <I>First</I>
and <I>last</I> can be any integer value so long as <I>first</I> is less than <I>last</I>. </DD>
</DL>
<P>
Vector
names must start with a letter and consist of letters, digits, or underscores.
<BR>
<CODE># Error: must start with letter<BR>
vector create 1abc<BR>
</CODE><P>You can automatically generate vector names using the "<I>#auto</I>" vector name.
The <B>create</B> operation will generate a unique vector name. <BR>
<CODE>set vec [vector create #auto]<BR>
puts "$vec has [$vec length] components"<BR>
<H3><A NAME="sect6" HREF="#toc6"></CODE><P>Vector Indices</A></H3>
Vectors are indexed by integers. You can access the individual
vector components via its array variable or Tcl command. The string representing
the index can be an integer, a numeric expression, a range, or a special
keyword. <P>
The index must lie within the current range of the vector, otherwise
an an error message is returned. Normally the indices of a vector are start
from 0. But you can use the <B>offset</B> operation to change a vector's indices
on-the-fly. <BR>
<CODE>puts $vecName(0)<BR>
vecName offset -5<BR>
puts $vecName(-5)<BR>
</CODE><P>You can also use numeric expressions as indices. The result of the expression
must be an integer value. <BR>
<CODE>set n 21<BR>
set vecName($n+3) 50.2<BR>
</CODE><P>The following special non-numeric indices are available: <I>min</I>, <I>max</I>, <I>end</I>,
and <I>++end</I>. <BR>
<CODE>puts "min = $vecName($min)"<BR>
set vecName(end) -1.2<BR>
</CODE><P>The indices <I>min</I> and <I>max</I> will return the minimum and maximum values of the
vector. The index <I>end</I> returns the value of the last component in the vector.
The index <I>++end</I> is used to append new value onto the vector. It automatically
extends the vector by one component and sets its value. <BR>
<CODE># Append an new component to the end<BR>
set vecName(++end) 3.2<BR>
</CODE><P>A range of indices can be indicated by a colon (:). <BR>
<CODE># Set the first six components to 1.0<BR>
set vecName(0:5) 1.0<BR>
</CODE><P>If no index is supplied the first or last component is assumed. <BR>
<CODE># Print the values of all the components<BR>
puts $vecName(:)<BR>
<H2><A NAME="sect7" HREF="#toc7"></CODE><P>Vector Operations</A></H2>
<DL>
<DT><B>vector create <I>vecName</I></B>?(<I>size</I>)?... ?<I>switches</I>? </DT>
<DD>The <B>create</B> operation
creates a new vector <I>vecName</I>. Both a Tcl command and array variable <I>vecName</I>
are also created. The name <I>vecName</I> must be unique, so another Tcl command
or array variable can not already exist in that scope. You can access the
components of the vector using its variable. If you change a value in the
array, or unset an array element, the vector is updated to reflect the
changes. When the variable <I>vecName</I> is unset, the vector and its Tcl command
are also destroyed. <P>
The vector has optional switches that affect how the
vector is created. They are as follows: <blockquote></DD>
<DT><B>-variable <I>varName</I></B> </DT>
<DD>Specifies the name
of a Tcl variable to be mapped to the vector. If the variable already exists,
it is first deleted, then recreated. If <I>varName</I> is the empty string, then
no variable will be mapped. You can always map a variable back to the vector
using the vector's <B>variable</B> operation. </DD>
<DT><B>-command <I>cmdName</I></B> </DT>
<DD>Maps a Tcl command
to the vector. The vector can be accessed using <I>cmdName</I> and one of the
vector instance operations. A Tcl command by that name cannot already
exist. If <I>cmdName</I> is the empty string, no command mapping will be made. </DD>
<DT><B>-watchunset
<I>boolean</I></B> </DT>
<DD>Indicates that the vector should automatically delete itself if
the variable associated with the vector is unset. By default, the vector
will not be deleted. This is different from previous releases. Set <I>boolean</I>
to "true" to get the old behavior. </DD>
</DL>
</blockquote>
<DL>
<DT><B>vector destroy <I>vecName</I></B> ?<I>vecName...</I>? </DT>
<DD></DD>
<DT><B>vector
expr <I>expression</I></B> </DT>
<DD><blockquote>All binary operators take vectors as operands (remember
that numbers are treated as one-component vectors). The exact action of
binary operators depends upon the length of the second operand. If the
second operand has only one component, then each element of the first vector
operand is computed by that value. For example, the expression "x * 2"
multiples all elements of the vector x by 2. If the second operand has
more than one component, both operands must be the same length. Each pair
of corresponding elements are computed. So "x + y" adds the the first components
of x and y together, the second, and so on. <P>
The valid operators are listed
below, grouped in decreasing order of precedence: </DD>
<DT><B>- !</B> </DT>
<DD>Unary minus and logical
NOT. The unary minus flips the sign of each component in the vector. The
logical not operator returns a vector of whose values are 0.0 or 1.0. For
each non-zero component 1.0 is returned, 0.0 otherwise. </DD>
<DT><B>^</B> </DT>
<DD>Exponentiation. </DD>
<DT><B>*
/ %</B> </DT>
<DD>Multiply, divide, remainder. </DD>
<DT><B>+ -</B> </DT>
<DD>Add and subtract. </DD>
<DT><B><< >></B> </DT>
<DD>Left and
right shift. Circularly shifts the values of the vector (not implemented
yet). </DD>
<DT><B>< > <= >=</B> </DT>
<DD>Boolean less, greater, less than or equal, and greater than
or equal. Each operator returns a vector of ones and zeros. If the condition
is true, 1.0 is the component value, 0.0 otherwise. </DD>
<DT><B>== !=</B> </DT>
<DD>Boolean equal
and not equal. Each operator returns a vector of ones and zeros. If the
condition is true, 1.0 is the component value, 0.0 otherwise. </DD>
<DT><B>|</B> </DT>
<DD>Bit-wise OR.
(Not implemented). </DD>
<DT><B>&&</B> </DT>
<DD>Logical AND. Produces a 1 result if both operands are
non-zero, 0 otherwise. </DD>
<DT><B>||</B> </DT>
<DD>Logical OR. Produces a 0 result if both operands
are zero, 1 otherwise. </DD>
<DT><I>x<B>?<I>y<B>:<I>z</I></B></I></B></I> </DT>
<DD>If-then-else, as in C. (Not implemented yet).
</DD>
</DL>
<P>
See the C manual for more details on the results produced by each operator.
All of the binary operators group left-to-right within the same precedence
level. <P>
Several mathematical functions are supported for vectors. Each
of the following functions invokes the math library function of the same
name; see the manual entries for the library functions for details on what
they do. The operation is applied to all elements of the vector returning
the results. <BR>
<CODE><P>
<B>acos</B><tt> </tt> <tt> </tt> <B>cos</B><tt> </tt> <tt> </tt> <B>hypot</B><tt> </tt> <tt> </tt> <B>sinh</B> <BR>
<B>asin</B><tt> </tt> <tt> </tt> <B>cosh</B><tt> </tt> <tt> </tt> <B>log</B><tt> </tt> <tt> </tt> <B>sqrt</B> <BR>
<B>atan</B><tt> </tt> <tt> </tt> <B>exp</B><tt> </tt> <tt> </tt> <B>log10</B><tt> </tt> <tt> </tt> <B>tan</B> <BR>
<B>ceil</B><tt> </tt> <tt> </tt> <B>floor</B><tt> </tt> <tt> </tt> <B>sin</B><tt> </tt> <tt> </tt> <B>tanh</B> <BR>
</CODE><P>Additional functions are:
<DL>
<DT><B>abs</B> </DT>
<DD>Returns the absolute value of each component.
</DD>
<DT><B>random</B> </DT>
<DD>Returns a vector of non-negative values uniformly distributed between
[0.0, 1.0) using <I>drand48</I>. The seed comes from the internal clock of the machine
or may be set manual with the srandom function. </DD>
<DT><B>round</B> </DT>
<DD>Rounds each component
of the vector. </DD>
<DT><B>srandom</B> </DT>
<DD>Initializes the random number generator using <I>srand48</I>.
The high order 32-bits are set using the integral portion of the first
vector component. All other components are ignored. The low order 16-bits
are set to an arbitrary value. </DD>
</DL>
<P>
The following functions return a single
value.
<DL>
<DT><B>adev</B> </DT>
<DD>Returns the average deviation (defined as the sum of the absolute
values of the differences between component and the mean, divided by the
length of the vector). </DD>
<DT><B>kurtosis</B> </DT>
<DD>Returns the degree of peakedness (fourth
moment) of the vector. </DD>
<DT><B>length</B> </DT>
<DD>Returns the number of components in the vector.
</DD>
<DT><B>max</B> </DT>
<DD>Returns the vector's maximum value. </DD>
<DT><B>mean</B> </DT>
<DD>Returns the mean value of the
vector. </DD>
<DT><B>median</B> </DT>
<DD>Returns the median of the vector. </DD>
<DT><B>min</B> </DT>
<DD>Returns the vector's
minimum value. </DD>
<DT><B>q1</B> </DT>
<DD>Returns the first quartile of the vector. </DD>
<DT><B>q3</B> </DT>
<DD>Returns the
third quartile of the vector. </DD>
<DT><B>prod</B> </DT>
<DD>Returns the product of the components.
</DD>
<DT><B>sdev</B> </DT>
<DD>Returns the standard deviation (defined as the square root of the
variance) of the vector. </DD>
<DT><B>skew</B> </DT>
<DD>Returns the skewness (or third moment) of
the vector. This characterizes the degree of asymmetry of the vector about
the mean. </DD>
<DT><B>sum</B> </DT>
<DD>Returns the sum of the components. </DD>
<DT><B>var</B> </DT>
<DD>Returns the variance
of the vector. The sum of the squared differences between each component
and the mean is computed. The variance is the sum divided by the length
of the vector minus 1. </DD>
</DL>
<P>
The last set returns a vector of the same length
as the argument.
<DL>
<DT><B>norm</B> </DT>
<DD>Scales the values of the vector to lie in the range
[0.0..1.0]. </DD>
<DT><B>sort</B> </DT>
<DD>Returns the vector components sorted in ascending order. </DD>
</DL>
</blockquote>
<DL>
<DT><B>vector
names </B>?<I>pattern</I>? </DT>
<DD></DD>
</DL>
<H2><A NAME="sect8" HREF="#toc8">Instance Operations</A></H2>
You can also use the vector's Tcl command
to query or modify it. The general form is <BR>
<P>
<CODE><I>vecName <I>operation</I></I> ?<I>arg</I>?...<BR>
</CODE><P>Both <I>operation</I> and its arguments determine the exact behavior of the command.
The operations available for vectors are listed below.
<DL>
<DT><I>vecName <B>append</B></I> <I>item</I>
?<I>item</I>?... </DT>
<DD>Appends the component values from <I>item</I> to <I>vecName</I>. <I>Item</I> can be either
the name of a vector or a list of numeric values. </DD>
<DT><I>vecName <B>clear</B></I> </DT>
<DD>Clears
the element indices from the array variable associated with <I>vecName</I>. This
doesn't affect the components of the vector. By default, the number of entries
in the Tcl array doesn't match the number of components in the vector. This
is because its too expensive to maintain decimal strings for both the index
and value for each component. Instead, the index and value are saved only
when you read or write an element with a new index. This command removes
the index and value strings from the array. This is useful when the vector
is large. </DD>
<DT><I>vecName <B>delete</B></I> <I>index</I> ?<I>index</I>?... </DT>
<DD>Deletes the <I>index</I>th component from
the vector <I>vecName</I>. <I>Index</I> is the index of the element to be deleted. This
is the same as unsetting the array variable element <I>index</I>. The vector is
compacted after all the indices have been deleted. </DD>
<DT><I>vecName <B>dup</B></I> <I>destName</I>
</DT>
<DD>Copies <I>vecName</I> to <I>destName</I>. <I>DestName</I> is the name of a destination vector.
If a vector <I>destName</I> already exists, it is overwritten with the components
of <I>vecName</I>. Otherwise a new vector is created. </DD>
<DT><I>vecName <B>expr</B></I> <I>expression</I>
</DT>
<DD>Computes the expression and resets the values of the vector accordingly.
Both scalar and vector math operations are allowed. All values in expressions
are either real numbers or names of vectors. All numbers are treated as
one component vectors. </DD>
<DT><I>vecName <B>length</B></I> ?<I>newSize</I>? </DT>
<DD>Queries or resets the number
of components in <I>vecName</I>. <I>NewSize</I> is a number specifying the new size of
the vector. If <I>newSize</I> is smaller than the current size of <I>vecName</I>, <I>vecName</I>
is truncated. If <I>newSize</I> is greater, the vector is extended and the new
components are initialized to <I>0.0</I>. If no <I>newSize</I> argument is present, the
current length of the vector is returned. </DD>
<DT><I>vecName <B>merge</B></I> <I>srcName</I> ?<I>srcName</I>?...
</DT>
<DD>Merges the named vectors into a single vector. The resulting vector is
formed by merging the components of each source vector one index at a
time. </DD>
<DT><I>vecName <B>notify</B></I> <I>keyword</I> </DT>
<DD>Controls how vector clients are notified of
changes to the vector. The exact behavior is determined by <I>keyword</I>. <blockquote></DD>
<DT><I>always</I>
</DT>
<DD>Indicates that clients are to be notified immediately whenever the vector
is updated. </DD>
<DT><I>never</I> </DT>
<DD>Indicates that no clients are to be notified. </DD>
<DT><I>whenidle</I>
</DT>
<DD>Indicates that clients are to be notified at the next idle point whenever
the vector is updated. </DD>
<DT><I>now</I> </DT>
<DD>If any client notifications is currently pending,
they are notified immediately. </DD>
<DT><I>cancel</I> </DT>
<DD>Cancels pending notifications of clients
using the vector. </DD>
<DT><I>pending</I> </DT>
<DD>Returns <I>1</I> if a client notification is pending,
and <I>0</I> otherwise. </DD>
</DL>
</blockquote>
<DL>
<DT><I>vecName <B>offset</B></I> ?<I>value</I>? </DT>
<DD>Shifts the indices of the vector
by the amount specified by <I>value</I>. <I>Value</I> is an integer number. If no <I>value</I>
argument is given, the current offset is returned. </DD>
<DT><I>vecName <B>populate</B></I> <I>destName</I>
?<I>density</I>? </DT>
<DD>Creates a vector <I>destName</I> which is a superset of <I>vecName</I>. <I>DestName</I>
will include all the components of <I>vecName</I>, in addition the interval between
each of the original components will contain a <I>density</I> number of new components,
whose values are evenly distributed between the original components values.
This is useful for generating abscissas to be interpolated along a spline.
</DD>
<DT><I>vecName <B>range</B></I> <I>firstIndex</I> ?<I>lastIndex</I>?... </DT>
<DD>Returns a list of numeric values representing
the vector components between two indices. Both <I>firstIndex</I> and <I>lastIndex</I>
are indices representing the range of components to be returned. If <I>lastIndex</I>
is less than <I>firstIndex</I>, the components are listed in reverse order. </DD>
<DT><I>vecName
<B>search</B></I> <I>value</I> ?<I>value</I>? </DT>
<DD>Searches for a value or range of values among the
components of <I>vecName</I>. If one <I>value</I> argument is given, a list of indices
of the components which equal <I>value</I> is returned. If a second <I>value</I> is also
provided, then the indices of all components which lie within the range
of the two values are returned. If no components are found, then <I>""</I> is returned.
</DD>
<DT><I>vecName <B>set</B></I> <I>item</I> </DT>
<DD>Resets the components of the vector to <I>item</I>. <I>Item</I> can be
either a list of numeric expressions or another vector. </DD>
<DT><I>vecName <B>seq</B></I> <I>start</I>
?<I>finish</I>? ?<I>step</I>? </DT>
<DD>Generates a sequence of values starting with the value
<I>start</I>. <I>Finish</I> indicates the terminating value of the sequence. The vector
is automatically resized to contain just the sequence. If three arguments
are present, <I>step</I> designates the interval. <P>
With only two arguments (no
<I>finish</I> argument), the sequence will continue until the vector is filled.
With one argument, the interval defaults to 1.0. </DD>
<DT><I>vecName <B>sort</B></I> ?<B>-reverse</B>?
?<I>argName</I>?... </DT>
<DD>Sorts the vector <I>vecName</I> in increasing order. If the <B>-reverse</B>
flag is present, the vector is sorted in decreasing order. If other arguments
<I>argName</I> are present, they are the names of vectors which will be rearranged
in the same manner as <I>vecName</I>. Each vector must be the same length as <I>vecName</I>.
You could use this to sort the x vector of a graph, while still retaining
the same x,y coordinate pairs in a y vector. </DD>
<DT><I>vecName <B>variable</B></I> <I>varName</I> </DT>
<DD>Maps
a Tcl variable to the vector, creating another means for accessing the
vector. The variable <I>varName</I> can't already exist. This overrides any current
variable mapping the vector may have. </DD>
</DL>
</blockquote>
<H2><A NAME="sect9" HREF="#toc9">C Language API</A></H2>
You can create, modify,
and destroy vectors from C code, using library routines. You need to
include the header file <I>blt.h</I>. It contains the definition of the structure
<B>Blt_Vector</B>, which represents the vector. It appears below. <BR>
<CODE>typedef struct {<BR>
double *<I>valueArr</I>; <BR>
int <I>numValues</I>; <BR>
int <I>arraySize</I>; <BR>
double <I>min</I>, <I>max</I>; <BR>
} <B>Blt_Vector</B>;<BR>
</CODE><P>The field <I>valueArr</I> points to memory holding the vector components. The
components are stored in a double precision array, whose size size is represented
by <I>arraySize</I>. <I>NumValues</I> is the length of vector. The size of the array
is always equal to or larger than the length of the vector. <I>Min</I> and <I>max</I>
are minimum and maximum component values.
<H2><A NAME="sect10" HREF="#toc10">Library Routines</A></H2>
The following
routines are available from C to manage vectors. Vectors are identified
by the vector name. <P>
<B>Blt_CreateVector</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_CreateVector</B> (<I>interp</I>, <I>vecName</I>, <I>length</I>, <I>vecPtrPtr</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
char *<I>vecName</I>;<BR>
int <I>length</I>;<BR>
Blt_Vector **<I>vecPtrPtr</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Creates a new vector <I>vecName</I> with a length of <I>length</I>. <B>Blt_CreateVector</B>
creates both a new Tcl command and array variable <I>vecName</I>. Neither a command
nor variable named <I>vecName</I> can already exist. A pointer to the vector
is placed into <I>vecPtrPtr</I>. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is successfully
created. If <I>length</I> is negative, a Tcl variable or command <I>vecName</I> already
exists, or memory cannot be allocated for the vector, then <I>TCL_ERROR</I> is
returned and <I>interp->result</I> will contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_DeleteVectorByName</B>
<blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_DeleteVectorByName</B> (<I>interp</I>, <I>vecName</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
char *<I>vecName</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Removes the vector <I>vecName</I>. <I>VecName</I> is the name of a vector
which must already exist. Both the Tcl command and array variable <I>vecName</I>
are destroyed. All clients of the vector will be notified immediately that
the vector has been destroyed. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is
successfully deleted. If <I>vecName</I> is not the name a vector, then <I>TCL_ERROR</I>
is returned and <I>interp->result</I> will contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_DeleteVector</B>
<blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_DeleteVector</B> (<I>vecPtr</I>)<BR>
<blockquote>Blt_Vector *<I>vecPtr</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Removes the vector pointed to by <I>vecPtr</I>. <I>VecPtr</I> is a pointer
to a vector, typically set by <B>Blt_GetVector</B> or <B>Blt_CreateVector</B>. Both the
Tcl command and array variable of the vector are destroyed. All clients
of the vector will be notified immediately that the vector has been destroyed.
</DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is successfully deleted. If <I>vecName</I>
is not the name a vector, then <I>TCL_ERROR</I> is returned and <I>interp->result</I> will
contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_GetVector</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_GetVector</B> (<I>interp</I>, <I>vecName</I>, <I>vecPtrPtr</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
char *<I>vecName</I>;<BR>
Blt_Vector **<I>vecPtrPtr</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Retrieves the vector <I>vecName</I>. <I>VecName</I> is the name of a vector
which must already exist. <I>VecPtrPtr</I> will point be set to the address of
the vector. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is successfully retrieved.
If <I>vecName</I> is not the name of a vector, then <I>TCL_ERROR</I> is returned and
<I>interp->result</I> will contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_ResetVector</B> <P>
<blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_ResetVector</B> (<I>vecPtr</I>, <I>dataArr</I>, <BR>
<tt> </tt> <tt> </tt> <I>numValues</I>, <I>arraySize</I>, <I>freeProc</I>)<BR>
<blockquote>Blt_Vector *<I>vecPtr</I>;<BR>
double *<I>dataArr</I>;<BR>
int *<I>numValues</I>;<BR>
int *<I>arraySize</I>;<BR>
Tcl_FreeProc *<I>freeProc</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Resets the components of the vector pointed to by <I>vecPtr</I>.
Calling <B>Blt_ResetVector</B> will trigger the vector to dispatch notifications
to its clients. <I>DataArr</I> is the array of doubles which represents the vector
data. <I>NumValues</I> is the number of elements in the array. <I>ArraySize</I> is the
actual size of the array (the array may be bigger than the number of values
stored in it). <I>FreeProc</I> indicates how the storage for the vector component
array (<I>dataArr</I>) was allocated. It is used to determine how to reallocate
memory when the vector is resized or destroyed. It must be <I>TCL_DYNAMIC</I>,
<I>TCL_STATIC</I>, <I>TCL_VOLATILE</I>, or a pointer to a function to free the memory
allocated for the vector array. If <I>freeProc</I> is <I>TCL_VOLATILE</I>, it indicates
that <I>dataArr</I> must be copied and saved. If <I>freeProc</I> is <I>TCL_DYNAMIC</I>, it indicates
that <I>dataArr</I> was dynamically allocated and that Tcl should free <I>dataArr</I>
if necessary. <I>Static</I> indicates that nothing should be done to release storage
for <I>dataArr</I>. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is successfully resized.
If <I>newSize</I> is negative, a vector <I>vecName</I> does not exist, or memory cannot
be allocated for the vector, then <I>TCL_ERROR</I> is returned and <I>interp->result</I>
will contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_ResizeVector</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_ResizeVector</B> (<I>vecPtr</I>, <I>newSize</I>)<BR>
<blockquote>Blt_Vector *<I>vecPtr</I>;<BR>
int <I>newSize</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Resets the length of the vector pointed to by <I>vecPtr</I> to <I>newSize</I>.
If <I>newSize</I> is smaller than the current size of the vector, it is truncated.
If <I>newSize</I> is greater, the vector is extended and the new components are
initialized to <I>0.0</I>. Calling <B>Blt_ResetVector</B> will trigger the vector to dispatch
notifications. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the vector is successfully resized.
If <I>newSize</I> is negative or memory can not be allocated for the vector,
then <I>TCL_ERROR</I> is returned and <I>interp->result</I> will contain an error message.
<P>
</DD>
</DL>
<P>
<B>Blt_VectorExists</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>int <B>Blt_VectorExists</B> (<I>interp</I>, <I>vecName</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
char *<I>vecName</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Indicates if a vector named <I>vecName</I> exists in <I>interp</I>. </DD>
<DT>Results:
</DT>
<DD>Returns <I>1</I> if a vector <I>vecName</I> exists and <I>0</I> otherwise. </DD>
</DL>
</blockquote>
<P>
<P>
If your application
needs to be notified when a vector changes, it can allocate a unique <I>client
identifier</I> for itself. Using this identifier, you can then register a call-back
to be made whenever the vector is updated or destroyed. By default, the
call-backs are made at the next idle point. This can be changed to occur
at the time the vector is modified. An application can allocate more than
one identifier for any vector. When the client application is done with
the vector, it should free the identifier. <P>
The call-back routine must of
the following type. <BR>
<blockquote><BR>
<CODE>typedef void (<B>Blt_VectorChangedProc</B>) (Tcl_Interp *<I>interp</I>, <BR>
<blockquote>ClientData <I>clientData</I>, Blt_VectorNotify <I>notify</I>);<BR>
</blockquote>
<BR>
</blockquote>
</PRE></CODE><P><I>ClientData</I> is passed to this routine whenever it is called. You can use
this to pass information to the call-back. The <I>notify</I> argument indicates
whether the vector has been updated of destroyed. It is an enumerated type.
<BR>
<blockquote><BR>
<CODE>typedef enum {<BR>
<I>BLT_VECTOR_NOTIFY_UPDATE</I>=1,<BR>
<I>BLT_VECTOR_NOTIFY_DESTROY</I>=2<BR>
} <B>Blt_VectorNotify</B>;<BR>
<BR>
</blockquote>
<P>
</CODE><P><B>Blt_AllocVectorId</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>Blt_VectorId <B>Blt_AllocVectorId</B> (<I>interp</I>, <I>vecName</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
char *<I>vecName</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Allocates an client identifier for with the vector <I>vecName</I>.
This identifier can be used to specify a call-back which is triggered when
the vector is updated or destroyed. </DD>
<DT>Results: </DT>
<DD>Returns a client identifier
if successful. If <I>vecName</I> is not the name of a vector, then <I>NULL</I> is returned
and <I>interp->result</I> will contain an error message. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_GetVectorById</B> <blockquote>
<DL>
<DT>Synopsis:
</DT>
<DD><BR>
<CODE>int <B>Blt_GetVector</B> (<I>interp</I>, <I>clientId</I>, <I>vecPtrPtr</I>)<BR>
<blockquote>Tcl_Interp *<I>interp</I>;<BR>
Blt_VectorId <I>clientId</I>;<BR>
Blt_Vector **<I>vecPtrPtr</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Retrieves the vector used by <I>clientId</I>. <I>ClientId</I> is a valid
vector client identifier allocated by <B>Blt_AllocVectorId</B>. <I>VecPtrPtr</I> will
point be set to the address of the vector. </DD>
<DT>Results: </DT>
<DD>Returns <I>TCL_OK</I> if the
vector is successfully retrieved. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_SetVectorChangedProc</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>void <B>Blt_SetVectorChangedProc</B> (<I>clientId</I>, <I>proc</I>, <I>clientData</I>);<BR>
<blockquote>Blt_VectorId <I>clientId</I>;<BR>
Blt_VectorChangedProc *<I>proc</I>;<BR>
ClientData *<I>clientData</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Specifies a call-back routine to be called whenever the vector
associated with <I>clientId</I> is updated or deleted. <I>Proc</I> is a pointer to call-back
routine and must be of the type <B>Blt_VectorChangedProc</B>. <I>ClientData</I> is a
one-word value to be passed to the routine when it is invoked. If <I>proc</I> is
<I>NULL</I>, then the client is not notified. </DD>
<DT>Results: </DT>
<DD>The designated call-back
procedure will be invoked when the vector is updated or destroyed. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_FreeVectorId</B>
<blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>void <B>Blt_FreeVectorId</B> (<I>clientId</I>);<BR>
<blockquote>Blt_VectorId <I>clientId</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Frees the client identifier. Memory allocated for the identifier
is released. The client will no longer be notified when the vector is
modified. </DD>
<DT>Results: </DT>
<DD>The designated call-back procedure will be no longer be
invoked when the vector is updated or destroyed. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_NameOfVectorId</B> <blockquote>
<DL>
<DT>Synopsis:
</DT>
<DD><BR>
<CODE>char *<B>Blt_NameOfVectorId</B> (<I>clientId</I>);<BR>
<blockquote>Blt_VectorId <I>clientId</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Retrieves the name of the vector associated with the client
identifier <I>clientId</I>. </DD>
<DT>Results: </DT>
<DD>Returns the name of the vector associated
with <I>clientId</I>. If <I>clientId</I> is not an identifier or the vector has been
destroyed, <I>NULL</I> is returned. </DD>
</DL>
</blockquote>
<P>
<P>
<B>Blt_InstallIndexProc</B> <blockquote>
<DL>
<DT>Synopsis: </DT>
<DD><BR>
<CODE>void <B>Blt_InstallIndexProc</B> (<I>indexName</I>, <I>procPtr</I>)<BR>
<blockquote>char *<I>indexName</I>;<BR>
Blt_VectorIndexProc *<I>procPtr</I>;<BR>
</DD>
</DL>
</blockquote>
<DL>
<DT></CODE><P>Description: </DT>
<DD>Registers a function to be called to retrieved the index
<I>indexName</I> from the vector's array variable. <P>
typedef double Blt_VectorIndexProc(Vector
*vecPtr); <P>
The function will be passed a pointer to the vector. The function
must return a double representing the value at the index. </DD>
<DT>Results: </DT>
<DD>The new
index is installed into the vector. </DD>
</DL>
</blockquote>
</blockquote>
<H2><A NAME="sect11" HREF="#toc11">C API Example</A></H2>
The following example opens
a file of binary data and stores it in an array of doubles. The array size
is computed from the size of the file. If the vector "data" exists, calling
<B>Blt_VectorExists</B>, <B>Blt_GetVector</B> is called to get the pointer to the vector.
Otherwise the routine <B>Blt_CreateVector</B> is called to create a new vector
and returns a pointer to it. Just like the Tcl interface, both a new Tcl
command and array variable are created when a new vector is created. It
doesn't make any difference what the initial size of the vector is since
it will be reset shortly. The vector is updated when <B>lt_ResetVector</B> is called.
Blt_ResetVector makes the changes visible to the Tcl interface and other
vector clients (such as a graph widget). <P>
<BR>
<CODE>#include <tcl.h><BR>
#include <blt.h><tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> <tt> </tt> <BR>
<!--
Blt_Vector *vecPtr;<BR>
double *newArr;<BR>
FILE *f;<BR>
struct stat statBuf;<BR>
int numBytes, numValues;<BR>
<P>
f = fopen("binary.dat", "r");<BR>
fstat(fileno(f), &statBuf);<BR>
numBytes = (int)statBuf.st_size;<BR>
<P>
/* Allocate an array big enough to hold all the data */<BR>
newArr = (double *)m<A HREF="alloc.n.html">alloc(numBytes)</A>
;<BR>
numValues = numBytes / sizeof(double);<BR>
fread((void *)newArr, numValues, sizeof(double), f);<BR>
fclose(f);<BR>
<P>
if (Blt_VectorExists(interp, "data")) {<BR>
if (Blt_GetVector(interp, "data", &vecPtr) != TCL_OK) {<BR>
<tt> </tt> <tt> </tt> return TCL_ERROR;<BR>
}<BR>
} else {<BR>
if (Blt_CreateVector(interp, "data", 0, &vecPtr) != TCL_OK) {<BR>
<tt> </tt> <tt> </tt> return TCL_ERROR;<BR>
}<BR>
}<BR>
/* <BR>
* Reset the vector. Clients will be notified when Tk is idle. <BR>
* TCL_DYNAMIC tells the vector to free the memory allocated <BR>
* if it needs to reallocate or destroy the vector.<BR>
*/<BR>
if (Blt_ResetVector(vecPtr, newArr, numValues, numValues, <BR>
<tt> </tt> <tt> </tt> TCL_DYNAMIC) != TCL_OK) {<BR>
return TCL_ERROR;<BR>
}<BR>
-->
<H2><A NAME="sect12" HREF="#toc12"></CODE><P>Incompatibilities</A></H2>
In previous versions, if the array variable isn't global
(i.e. local to a Tcl procedure), the vector is automatically destroyed
when the procedure returns. <BR>
<CODE>proc doit {} {<BR>
# Temporary vector x<BR>
vector x(10)<BR>
set <A HREF="x.9.html">x(9)</A>
2.0<BR>
...<BR>
}<BR>
<P>
</CODE><P>This has changed. Variables are not automatically destroyed when their
variable is unset. You can restore the old behavior by setting the "-watchunset"
switch.
<H2><A NAME="sect13" HREF="#toc13"></CODE><P>Keywords</A></H2>
vector, graph, widget <P>
<HR><P>
<A NAME="toc"><B>Table of Contents</B></A><P>
<UL>
<LI><A NAME="toc0" HREF="#sect0">Name</A></LI>
<LI><A NAME="toc1" HREF="#sect1">Synopsis</A></LI>
<LI><A NAME="toc2" HREF="#sect2">Description</A></LI>
<LI><A NAME="toc3" HREF="#sect3">Introduction</A></LI>
<LI><A NAME="toc4" HREF="#sect4">Example</A></LI>
<LI><A NAME="toc5" HREF="#sect5">Syntax</A></LI>
<UL>
<LI><A NAME="toc6" HREF="#sect6">Vector Indices</A></LI>
</UL>
<LI><A NAME="toc7" HREF="#sect7">Vector Operations</A></LI>
<LI><A NAME="toc8" HREF="#sect8">Instance Operations</A></LI>
<LI><A NAME="toc9" HREF="#sect9">C Language API</A></LI>
<LI><A NAME="toc10" HREF="#sect10">Library Routines</A></LI>
<LI><A NAME="toc11" HREF="#sect11">C API Example</A></LI>
<LI><A NAME="toc12" HREF="#sect12">Incompatibilities</A></LI>
<LI><A NAME="toc13" HREF="#sect13">Keywords</A></LI>
</UL>
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