<?xml version="1.0" encoding="UTF-8"?>
<!--
 * Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
 * Copyright (C) 2008 - INRIA
 * Copyright (C) 2015 - Samuel GOUGEON
 * Copyright (C) 2012 - 2016 - Scilab Enterprises
 *
 * This file is hereby licensed under the terms of the GNU GPL v2.0,
 * pursuant to article 5.3.4 of the CeCILL v.2.1.
 * This file was originally licensed under the terms of the CeCILL v2.1,
 * and continues to be available under such terms.
 * For more information, see the COPYING file which you should have received
 * along with this program.
 *
 -->
<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:ns5="http://www.w3.org/1999/xhtml" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org" xml:id="isreal" xml:lang="en">
    <refnamediv>
        <refname>isreal</refname>
        <refpurpose>check if a variable is stored as a complex matrix</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title>Syntax</title>
        <synopsis>t = isreal(x)
            t = isreal(x, eps)
        </synopsis>
    </refsynopsisdiv>
    <refsection>
        <title>Arguments</title>
        <variablelist>
            <varlistentry>
                <term>x</term>
                <listitem>
                    <para>Matrices of real or complex numbers (full or sparse storage).
                    Matrices of polynomials or rationals, with real or complex coefficients.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>eps</term>
                <listitem>
                    <para>a positive or null real (default value = 0)</para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>t</term>
                <listitem>
                    <para>a boolean</para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsection>
    <refsection>
        <title>Description</title>
        <para>
            <literal>isreal(x)</literal> returns %T (true) if <literal>x</literal> is
            stored as a real variable, and %F (false) <literal>x</literal> is stored with
            an (eventually zero) imaginary part.
        </para>
        <para>
            <literal>isreal(x, eps)</literal> returns %T (true) if
            <literal>x</literal> is stored as a real variable, or if the maximal absolute
            value of imaginary parts of its components is less or equal than <literal>eps</literal>.
        </para>
    </refsection>
    <refsection>
        <title>Examples</title>
        <programlisting role="example"><![CDATA[
isreal([])        // => %T
isreal([1 2])
isreal(1+0*%i)
isreal(1+0*%i,0)

// Sparse matrix:
isreal(sparse([1-%i -3+4*%i]))

// Polynomial:
p = (1-2*%s)^2
isreal(p)

// Rational fraction:
r = [ (%i-%s)/%s^2 %s/(2-%s)]
isreal(r)
 ]]></programlisting>
    </refsection>
    <refsection role="history">
        <title>History</title>
        <revhistory>
            <revision>
                <revnumber>6.0</revnumber>
                <revdescription>Extension to rationals
                </revdescription>
            </revision>
        </revhistory>
    </refsection>
</refentry>
