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<a name="Terminal-Output"></a>
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<p>
Next: <a href="Terminal-Input.html#Terminal-Input" accesskey="n" rel="next">Terminal Input</a>, Up: <a href="Basic-Input-and-Output.html#Basic-Input-and-Output" accesskey="u" rel="up">Basic Input and Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Terminal-Output-1"></a>
<h4 class="subsection">14.1.1 Terminal Output</h4>
<p>Since Octave normally prints the value of an expression as soon as it
has been evaluated, the simplest of all I/O functions is a simple
expression. For example, the following expression will display the
value of ‘<samp>pi</samp>’
</p>
<div class="example">
<pre class="example">pi
-| pi = 3.1416
</pre></div>
<p>This works well as long as it is acceptable to have the name of the
variable (or ‘<samp>ans</samp>’) printed along with the value. To print the
value of a variable without printing its name, use the function
<code>disp</code>.
</p>
<p>The <code>format</code> command offers some control over the way Octave prints
values with <code>disp</code> and through the normal echoing mechanism.
</p>
<a name="XREFdisp"></a><dl>
<dt><a name="index-disp"></a><em></em> <strong>disp</strong> <em>(<var>x</var>)</em></dt>
<dt><a name="index-disp-1"></a><em><var>str</var> =</em> <strong>disp</strong> <em>(<var>x</var>)</em></dt>
<dd><p>Display the value of <var>x</var>.
</p>
<p>For example:
</p>
<div class="example">
<pre class="example">disp ("The value of pi is:"), disp (pi)
-| the value of pi is:
-| 3.1416
</pre></div>
<p>Note that the output from <code>disp</code> always ends with a newline.
</p>
<p>If an output value is requested, <code>disp</code> prints nothing and returns the
formatted output in a string.
</p>
<p><strong>See also:</strong> <a href="Simple-File-I_002fO.html#XREFfdisp">fdisp</a>.
</p></dd></dl>
<a name="XREFlist_005fin_005fcolumns"></a><dl>
<dt><a name="index-list_005fin_005fcolumns"></a><em></em> <strong>list_in_columns</strong> <em>(<var>arg</var>, <var>width</var>, <var>prefix</var>)</em></dt>
<dd><p>Return a string containing the elements of <var>arg</var> listed in columns with
an overall maximum width of <var>width</var> and optional prefix <var>prefix</var>.
</p>
<p>The argument <var>arg</var> must be a cell array of character strings or a
character array.
</p>
<p>If <var>width</var> is not specified or is an empty matrix, or less than or equal
to zero, the width of the terminal screen is used. Newline characters are
used to break the lines in the output string. For example:
</p>
<div class="smallexample">
<pre class="smallexample">list_in_columns ({"abc", "def", "ghijkl", "mnop", "qrs", "tuv"}, 20)
⇒ abc mnop
def qrs
ghijkl tuv
whos ans
⇒
Variables in the current scope:
Attr Name Size Bytes Class
==== ==== ==== ===== =====
ans 1x37 37 char
Total is 37 elements using 37 bytes
</pre></div>
<p><strong>See also:</strong> <a href="#XREFterminal_005fsize">terminal_size</a>.
</p></dd></dl>
<a name="XREFterminal_005fsize"></a><dl>
<dt><a name="index-terminal_005fsize"></a><em></em> <strong>terminal_size</strong> <em>()</em></dt>
<dd><p>Return a two-element row vector containing the current size of the terminal
window in characters (rows and columns).
</p>
<p><strong>See also:</strong> <a href="#XREFlist_005fin_005fcolumns">list_in_columns</a>.
</p></dd></dl>
<a name="XREFformat"></a><dl>
<dt><a name="index-format"></a><em></em> <strong>format</strong></dt>
<dt><a name="index-format-1"></a><em></em> <strong>format</strong> <em>options</em></dt>
<dt><a name="index-format-2"></a><em>[<var>format</var>, <var>formatspacing</var>] =</em> <strong>format</strong></dt>
<dd><p>Reset or specify the format of the output produced by <code>disp</code> and Octave’s
normal echoing mechanism.
</p>
<p>This command only affects the display of numbers, but not how they are stored
or computed. To change the internal representation from the default double use
one of the conversion functions such as <code>single</code>, <code>uint8</code>,
<code>int64</code>, etc.
</p>
<p>By default, Octave displays 5 significant digits in a human readable form
(option ‘<samp>short</samp>’ paired with ‘<samp>loose</samp>’ format for matrices). If
<code>format</code> is invoked without any options, this default format is restored.
</p>
<p>Valid formats for floating point numbers are listed in the following
table.
</p>
<dl compact="compact">
<dt><code>short</code></dt>
<dd><p>Fixed point format with 5 significant figures (default).
</p>
</dd>
<dt><code>long</code></dt>
<dd><p>Fixed point format with 16 significant figures.
</p>
<p>As with the ‘<samp>short</samp>’ format, Octave will switch to an exponential ‘<samp>e</samp>’
format if it is unable to format a matrix properly using the current format.
</p>
</dd>
<dt><code>short e</code></dt>
<dt><code>long e</code></dt>
<dd><p>Exponential format. The number to be represented is split between a mantissa
and an exponent (power of 10). The mantissa has 5 significant digits in the
short format. In the long format, double values are displayed with 16
significant digits and single values are displayed with 8. For example,
with the ‘<samp>short e</samp>’ format, <code>pi</code> is displayed as <code>3.1416e+00</code>.
</p>
</dd>
<dt><code>short E</code></dt>
<dt><code>long E</code></dt>
<dd><p>Identical to ‘<samp>short e</samp>’ or ‘<samp>long e</samp>’ but displays an uppercase ‘<samp>E</samp>’
to indicate the exponent. For example, with the ‘<samp>long E</samp>’ format,
<code>pi</code> is displayed as <code>3.141592653589793E+00</code>.
</p>
</dd>
<dt><code>short g</code></dt>
<dt><code>long g</code></dt>
<dd><p>Optimally choose between fixed point and exponential format based on the
magnitude of the number. For example, with the ‘<samp>short g</samp>’ format,
<code>pi .^ [2; 4; 8; 16; 32]</code> is displayed as
</p>
<div class="example">
<pre class="example">ans =
9.8696
97.409
9488.5
9.0032e+07
8.1058e+15
</pre></div>
</dd>
<dt><code>short eng</code></dt>
<dt><code>long eng</code></dt>
<dd><p>Identical to ‘<samp>short e</samp>’ or ‘<samp>long e</samp>’ but displays the value using an
engineering format, where the exponent is divisible by 3. For example, with
the ‘<samp>short eng</samp>’ format, <code>10 * pi</code> is displayed as <code>31.416e+00</code>.
</p>
</dd>
<dt><code>long G</code></dt>
<dt><code>short G</code></dt>
<dd><p>Identical to ‘<samp>short g</samp>’ or ‘<samp>long g</samp>’ but displays an uppercase ‘<samp>E</samp>’
to indicate the exponent.
</p>
</dd>
<dt><code>free</code></dt>
<dt><code>none</code></dt>
<dd><p>Print output in free format, without trying to line up columns of matrices on
the decimal point. This is a raw format equivalent to the C++ code
<code>std::cout << <var>variable</var></code>. In general, the result is a presentation
with 6 significant digits where unnecessary precision (such as trailing zeros
for integers) is suppressed. Complex numbers are formatted as numeric pairs
like this ‘<samp>(0.60419, 0.60709)</samp>’ instead of like this
‘<samp>0.60419 + 0.60709i</samp>’.
</p></dd>
</dl>
<p>The following formats affect all numeric output (floating point and integer
types).
</p>
<dl compact="compact">
<dt><code>"+"</code></dt>
<dt><code>"+"</code> <code>"<var>chars</var>"</code></dt>
<dt><code>plus</code></dt>
<dt><code>plus <var>chars</var></code></dt>
<dd><p>Print a ‘<samp>+</samp>’ symbol for matrix elements greater than zero, a ‘<samp>-</samp>’
symbol for elements less than zero, and a space for zero matrix elements. This
format can be useful for examining the sparsity structure of a large matrix.
For very large matrices the function <code>spy</code> which plots the sparsity
pattern will be clearer.
</p>
<p>The optional argument <var>chars</var> specifies a list of 3 characters to use for
printing values greater than zero, less than zero, and equal to zero. For
example, with the format <code>"+" "+-."</code>, the matrix
<code>[1, 0, -1; -1, 0, 1]</code> is displayed as
</p>
<div class="example">
<pre class="example">ans =
+.-
-.+
</pre></div>
</dd>
<dt>bank</dt>
<dd><p>Print variable in a format appropriate for a currency (fixed format with two
digits to the right of the decimal point). Only the real part of a variable is
displayed, as the imaginary part makes no sense for a currency.
</p>
</dd>
<dt>native-hex</dt>
<dd><p>Print the hexadecimal representation of numbers as they are stored in memory.
For example, on a workstation which stores 8 byte real values in IEEE format
with the least significant byte first, the value of <code>pi</code> when printed in
<code>native-hex</code> format is <code>400921fb54442d18</code>.
</p>
</dd>
<dt>hex</dt>
<dd><p>The same as <code>native-hex</code>, but always print the most significant byte
first.
</p>
</dd>
<dt>native-bit</dt>
<dd><p>Print the bit representation of numbers as stored in memory. For example, the
value of <code>pi</code> is
</p>
<div class="example">
<pre class="example">01000000000010010010000111111011
01010100010001000010110100011000
</pre></div>
<p>(shown here in two 32 bit sections for typesetting purposes) when printed in
native-bit format on a workstation which stores 8 byte real values in IEEE
format with the least significant byte first.
</p>
</dd>
<dt>bit</dt>
<dd><p>The same as <code>native-bit</code>, but always print the most significant bits
first.
</p>
</dd>
<dt>rat</dt>
<dd><p>Print a rational approximation, i.e., values are approximated as the ratio of
small integers. For example, with the ‘<samp>rat</samp>’ format, <code>pi</code> is
displayed as <code>355/113</code>.
</p></dd>
</dl>
<p>The following two options affect the display of all matrices.
</p>
<dl compact="compact">
<dt><code>compact</code></dt>
<dd><p>Remove blank lines around column number labels and between matrices producing
more compact output with more data per page.
</p>
</dd>
<dt><code>loose</code></dt>
<dd><p>Insert blank lines above and below column number labels and between matrices to
produce a more readable output with less data per page. (default).
</p></dd>
</dl>
<p>If called with one or two output arguments, and no inputs, return the current
format and format spacing.
</p>
<p><strong>See also:</strong> <a href="Matrices.html#XREFfixed_005fpoint_005fformat">fixed_point_format</a>, <a href="Matrices.html#XREFoutput_005fprecision">output_precision</a>, <a href="Matrices.html#XREFsplit_005flong_005frows">split_long_rows</a>, <a href="Empty-Matrices.html#XREFprint_005fempty_005fdimensions">print_empty_dimensions</a>, <a href="Rational-Approximations.html#XREFrats">rats</a>.
</p></dd></dl>
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