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Chapters:
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<a href="Introduction.html">1: Introduction</a><br>
<a href="SimpleExample.html">2: Simple example</a><br>
<a href="InvokingGri.html">3: Invocation</a><br>
<a href="GettingMoreControl.html">4: Finer Control</a><br>
<a href="X-Y.html">5: X-Y Plots</a><br>
<a href="ContourPlots.html">6: Contour Plots</a><br>
<a href="Images.html">7: Image Plots</a><br>
<a href="Examples.html">8: Examples</a><br>
<a href="Commands.html">9: Gri Commands</a><br>
<a href="Programming.html">10: Programming</a><br>
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<a href="TestSuite.html">16: Test Suite</a><br>
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<a href="BuiltinIndex.html"><i>Variables</i></a><br>
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<h3>10.9.5: Unary Operators</h3>
Unary operators replace the last item on the stack with another item.
For example, the `<font color="#82140F"><code>sin</code></font>' operator takes the sine of the number on the
top of the stack; e.g., `<font color="#82140F"><code>{rpn 45 sin}</code></font>' yields the sine of 45 degrees.
<p>
The unary operators are illustrated below, in rough alphabetical order.
<p>
<dl>
<dt> <tt>{rpn 0 !}</tt>
<dd>Replace 0 (false) with its logical negation 1 (true).
<p>
<dt> <tt>{rpn -3 abs}</tt>
<dd>Calculate the absolute value of `<font color="#82140F"><code>-3</code></font>'.
<p>
<dt> <tt>{rpn 0.5 acos}</tt>
<dd>Calculate the inverse cosine of 0.5, yielding 60 (degrees).
<p>
<dt> <tt>{rpn 2 acosh}</tt>
<dd>Calculate the inverse hyperbolic cosine of 2, yielding 1.317. (Note:
argument must equal or exceed 1, or an error results.)
<p>
<dt> <tt>{rpn y x area}</tt>
<dd>Calculate the area under the curve y=y(x). For details
(see <a href="ManipulatingColumns.html#ManipulationofColumnsetc">Manipulation of Columns etc</a>).
<p>
<dt> <tt>{rpn 0.5 asin}</tt>
<dd>Calculate the inverse sine of 0.5, yielding 30 (degrees).
<p>
<dt> <tt>{rpn 1 atan}</tt>
<dd>Calculate the inverse tangent of 1, yielding 45 (degrees).
<p>
<dt> <tt>{rpn 0.5 atanh}</tt>
<dd>Calculate the inverse hyperbolic tangent of 0.5, yielding 0.549306
(radians).
<p>
<dt> <tt>{rpn 0 argv}</tt>
<dd>Returns the name of the Gri command-file, which is considered as the first
"optional" argument. (It may seem odd that the name of the command-file
is considered an option, but Gri does this for consistency with C and
other languages. It is useful.) Other arguments provided when Gri
was invoked are provided as `<font color="#82140F"><code>rpn 1 argv</code></font>', etc.
<p>
A string consisting of a single blank character results if one tries to
access beyond the list of arguments that were actually supplied. See
also the `<font color="82140F"><code>argc</code></font>' solitary operator (see <a href="SolitaryOperators.html#SolitaryOperators">Solitary Operators</a>), which
returns the number of optional arguments.
<p>
For example, if Gri is invoked as
<p>
<TABLE SUMMARY="Example" BORDER="0" BGCOLOR="#efefef" WIDTH="100%">
<TR>
<TD>
<PRE>
<font color="#82140F">
gri myscript.gri file1.dat file2.dat
</font></PRE>
</TD>
</TR>
</TABLE>
<p>
<p>
and if `<font color="#82140F"><samp>myscript.gri</samp></font>' contained
<p>
<TABLE SUMMARY="Example" BORDER="0" BGCOLOR="#efefef" WIDTH="100%">
<TR>
<TD>
<PRE>
<font color="#82140F">
.n. = {rpn argc}
.i. = 0
while {rpn .n. .i. <}
show "argument " .i. " is " {rpn .i. argv}
.i. += 1
end while
</font></PRE>
</TD>
</TR>
</TABLE>
<p>
<p>
then the output would be
<p>
<TABLE SUMMARY="Example" BORDER="0" BGCOLOR="#efefef" WIDTH="100%">
<TR>
<TD>
<PRE>
<font color="#82140F">
argument 0 is myscript.gri
argument 1 is file1.dat
argument 2 is file2.dat
</font></PRE>
</TD>
</TR>
</TABLE>
<p>
For usage within the Emacs gri-mode, see
see <a href="Emacs5.html#Filenameargumentswhenrunninggri">Filename arguments when running gri</a>.
<p>
<dt> <tt>{rpn "hi" ascent}</tt>
<dd>Determine ascent of this string (in cm), in the present font and
fontsize. (See also `<font color="#82140F"><code>descent</code></font>' and `<font color="#82140F"><code>width</code></font>'.)
<p>
<dt> <tt>{rpn "3.1" atof}</tt>
<dd>Calculate the numerical value contained in indicated string.
<p>
<dt> <tt>{rpn 1.5 ceil}</tt>
<dd>Calculate the next higher integer, yielding 2. (Opposite of `<font color="#82140F"><code>floor</code></font>'.)
<p>
<dt> <tt>{rpn 45 cos}</tt>
<dd>Calculate the cosine of 45 degrees, yielding 0.707.
<p>
<dt> <tt>{rpn 1 cosh}</tt>
<dd>Calculate the hyperbolic cosine of 1 (radian), yielding 1.543.
<p>
<dt> <tt>{rpn 1 cmtopt}</tt>
<dd>Convert from 1 centimeter to so-called ``point'' units, yielding 28.45.
(Opposite of `<font color="#82140F"><code>pttocm</code></font>'.)
<p>
<dt> <tt>{rpn "\\syn" defined}</tt>
<dd>Test whether the synonym is defined at the moment, returning 1 if
so and 0 if not. (Note the double-backslash in the synonym name, which
is required.)
<p>
<dt> <tt>{rpn ".var." defined}</tt>
<dd>Test whether the variable is defined at the moment, returning 1 if
so and 0 if not.
<p>
<dt> <tt>{rpn "\\@alias" defined}</tt>
<dd>Test whether the variable/synonym item that is named by the alias
(see <a href="Synonyms.html#AliasSynonyms">Alias Synonyms</a>) is defined at the moment, returning 1 if so and 0
if not.
<p>
<p>
<p>
<dt> <tt>{rpn "hi" descent}</tt>
<dd>Calculate the descent (below the baseline in cm) for the given string,
in the present font and fontsize. (See also `<font color="#82140F"><code>ascent</code></font>' and
`<font color="#82140F"><code>width</code></font>'.)
<p>
<dt> <tt>{rpn "/home/me/data/timeseries" directory_exists}</tt>
<dd>Determine whether indicate directory exists, yielding `<font color="#82140F"><code>1</code></font>' if it does
and `<font color="#82140F"><code>0</code></font>' otherwise. (See also `<font color="#82140F"><code>file_exists</code></font>'.)
<p>
<dt> <tt>{rpn 2 dup}</tt>
<dd>Duplicate the top item on stack, yielding `<font color="#82140F"><code>2 2</code></font>' on the stack.
(See also `<font color="#82140F"><code>exch</code></font>' and `<font color="#82140F"><code>pop</code></font>'.)
<p>
<dt> <tt>{rpn 1 exp}</tt>
<dd>Calculate the value of `<font color="#82140F"><code>e</code></font>' raised to the indicated power, yielding 2.71828.
<p>
<dt> <tt>{rpn 2 exp10}</tt>
<dd>Calculate the value of `<font color="#82140F"><code>10</code></font>' raised to the indicated power, yielding 100.
<p>
<dt> <tt>{rpn "foo.dat" file_exists}</tt>
<dd>Determine whether the indicate file exists, yielding `<font color="#82140F"><code>1</code></font>' if it does
and `<font color="#82140F"><code>0</code></font>' otherwise. (See also `<font color="#82140F"><code>directory_exists</code></font>'.)
<p>
<dt> <tt>{rpn 1.5 floor}</tt>
<dd>Calculate the nearest smaller integer, yielding 1. (Opposite of
`<font color="#82140F"><code>ceil</code></font>'.)
<p>
<dt> <tt>{rpn 3 ismissing}</tt>
<dd>Yields 1 if the indicated value is a ``missing value'' or 0 otherwise.
<p>
<dt> <tt>{rpn 100 log}</tt>
<dd>Calculate the base-10 logarithm of 100, yielding 2.
<p>
<dt> <tt>{rpn 10 ln}</tt>
<dd>Calculate the natural logarithm of 10, yielding 2.30259.
<p>
<dt> <tt>{rpn x mean}</tt>
<dd>Yields the mean value of the (non-missing) numbers in the x column. A
similar form also works for `<font color="#82140F"><code>y</code></font>', etc.
(see <a href="ManipulatingColumns.html#ManipulationofColumnsetc">Manipulation of Columns etc</a>).
<p>
<dt> <tt>{rpn x max}</tt>
<dd>Yields the largest value of the (non-missing) numbers in the x column. A
similar form also works for `<font color="#82140F"><code>y</code></font>', etc.
(see <a href="ManipulatingColumns.html#ManipulationofColumnsetc">Manipulation of Columns etc</a>).
<p>
<dt> <tt>{rpn x min}</tt>
<dd>Yields the smallest value of the (non-missing) numbers in the x column. A
similar form also works for `<font color="#82140F"><code>y</code></font>', etc.
(see <a href="ManipulatingColumns.html#ManipulationofColumnsetc">Manipulation of Columns etc</a>).
<p>
<dt> <tt>{rpn 28.45 pttocm}</tt>
<dd>Calculate the number of centimeters in 28.45 printers points, yielding 1.
(Opposite of `<font color="#82140F"><code>cmtopt</code></font>'.)
<p>
<dt> <tt>{rpn 1 2 pop}</tt>
<dd>Remove the top item from the stack, yielding `<font color="#82140F"><code>1</code></font>' on the stack.
Generates an error if the stack is empty. (See also `<font color="#82140F"><code>exch</code></font>' and
`<font color="#82140F"><code>dup</code></font>'.)
<p>
<dt> <tt>{rpn 4 sqrt}</tt>
<dd>Calculate the square root of 4, yielding 2. (Negative arguments yield
errors.)
<p>
<dt> <tt>{rpn 45 sin}</tt>
<dd>Calculate the sine of 45 (degrees), yielding 0.707107.
<p>
<dt> <tt>{rpn 2 sinh}</tt>
<dd>Calculate the hyperbolic sine of 2, yielding 3.62686.
<p>
<dt> <tt>{rpn "hello" strlen}</tt>
<dd>Determine the number of characters in string, e.g. 6 here.
<p>
<dt> <tt>{rpn "date" system}</tt>
<dd>Call the indicated system function and insert its ouput on the stack,
yielding the date as a character string.
<p>
<dt> <tt>{rpn 45 tan}</tt>
<dd>Calculate the tangent of 45 (degrees), yielding 1.
<p>
<dt> <tt>{rpn tanh}</tt>
<dd>Calculate the hyperbolic tangent of 2, yielding 0.964028.
<p>
<dt> <tt>{rpn "hi" width}</tt>
<dd>Determine width of this string (in cm), in the present font and fontsize.
(See also `<font color="#82140F"><code>ascent</code></font>' and `<font color="#82140F"><code>descent</code></font>'.)
<p>
<dt> <tt>{rpn 0 wordv}</tt>
<dd>Returns the first word used in invoking the present command. Similar
to the `<font color="82140F"><code>\.word0.</code></font>' synonym (see <a href="Synonyms.html#LocalSynonyms">Local Synonyms</a>). Example:
<p>
<TABLE SUMMARY="Example" BORDER="0" BGCOLOR="#efefef" WIDTH="100%">
<TR>
<TD>
<PRE>
<font color="#82140F">
`let us test .it.'
{
.w. = 0
while {rpn .w. wordc >}
show "The " .w. "-th word is `" {rpn .w. wordv} "'."
.w. += 1
end while
}
let us test "this thing"
let us test "this" "thing"
let us test "Pi is" {rpn 3.14}
</font></PRE>
</TD>
</TR>
</TABLE>
<p>
If you are using this to parse options given to the command, it is up to
you to skip the non-optional words in the command. In this case, for
example, we skipped the first three words (`<font color="#82140F"><code>let</code></font>', `<font color="#82140F"><code>us</code></font>', and
`<font color="#82140F"><code>test</code></font>').
<p>
<dt> <tt>{rpn 1 xusertocm}</tt>
<dd>Calculate the x coordinate, in centimeters measured from left-hand side of
page, corresponding to a user-value of x=1. (Opposite of
`<font color="#82140F"><code>xcmtouser</code></font>'.)
<p>
<dt> <tt>{rpn 1 xcmtouser}</tt>
<dd>Calculate the x value, in user units, for a point that is 1 centimeter from
the left-hand edge of the paper. (Opposite of `<font color="#82140F"><code>xusertocm</code></font>'.)
<p>
<dt> <tt>{rpn 1 yusertocm}</tt>
<dd>Calculate the y coordinate, in centimeters measured from bottom side of
page, corresponding to a user-value of x=1. (Opposite of
`<font color="#82140F"><code>ycmtouser</code></font>'.)
<p>
<dt> <tt>{rpn 1 ycmtouser}</tt>
<dd>Calculate the y value, in user units, for a point that is 1 centimeter from
the bottom edge of the paper. (Opposite of `<font color="#82140F"><code>yusertocm</code></font>'.)
<p>
<p>
</dl>
</table>
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