<html lang="en"> <head> <title>Numeric Data Types - Untitled</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="Untitled"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="prev" href="Data-Types.html#Data-Types" title="Data Types"> <link rel="next" href="Strings.html#Strings" title="Strings"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="Numeric-Data-Types"></a> <p> Next: <a rel="next" accesskey="n" href="Strings.html#Strings">Strings</a>, Previous: <a rel="previous" accesskey="p" href="Data-Types.html#Data-Types">Data Types</a>, Up: <a rel="up" accesskey="u" href="index.html#Top">Top</a> <hr> </div> <h2 class="chapter">4 Numeric Data Types</h2> <p><a name="index-numeric-constant-211"></a><a name="index-numeric-value-212"></a> A <dfn>numeric constant</dfn> may be a scalar, a vector, or a matrix, and it may contain complex values. <p>The simplest form of a numeric constant, a scalar, is a single number that can be an integer, a decimal fraction, a number in scientific (exponential) notation, or a complex number. Note that by default numeric constants are represented within Octave in double-precision floating point format (complex constants are stored as pairs of double-precision floating point values). It is however possible to represent real integers as described in <a href="Integer-Data-Types.html#Integer-Data-Types">Integer Data Types</a>. Here are some examples of real-valued numeric constants, which all have the same value: <pre class="example"> 105 1.05e+2 1050e-1 </pre> <p>To specify complex constants, you can write an expression of the form <pre class="example"> 3 + 4i 3.0 + 4.0i 0.3e1 + 40e-1i </pre> <p class="noindent">all of which are equivalent. The letter ‘<samp><span class="samp">i</span></samp>’ in the previous example stands for the pure imaginary constant, defined as <code>sqrt (-1)</code>. <p>For Octave to recognize a value as the imaginary part of a complex constant, a space must not appear between the number and the ‘<samp><span class="samp">i</span></samp>’. If it does, Octave will print an error message, like this: <pre class="example"> octave:13> 3 + 4 i parse error: syntax error >>> 3 + 4 i ^ </pre> <p class="noindent">You may also use ‘<samp><span class="samp">j</span></samp>’, ‘<samp><span class="samp">I</span></samp>’, or ‘<samp><span class="samp">J</span></samp>’ in place of the ‘<samp><span class="samp">i</span></samp>’ above. All four forms are equivalent. <!-- ov-re-mat.cc --> <p><a name="doc_002ddouble"></a> <div class="defun"> — Built-in Function: <b>double</b> (<var>x</var>)<var><a name="index-double-213"></a></var><br> <blockquote><p>Convert <var>x</var> to double precision type. <!-- Texinfo @sp should work but in practice produces ugly results for HTML. --> <!-- A simple blank line produces the correct behavior. --> <!-- @sp 1 --> <p class="noindent"><strong>See also:</strong> <a href="doc_002dsingle.html#doc_002dsingle">single</a>. </p></blockquote></div> <!-- data.cc --> <p><a name="doc_002dcomplex"></a> <div class="defun"> — Built-in Function: <b>complex</b> (<var>x</var>)<var><a name="index-complex-214"></a></var><br> — Built-in Function: <b>complex</b> (<var>re, im</var>)<var><a name="index-complex-215"></a></var><br> <blockquote><p>Return a complex result from real arguments. With 1 real argument <var>x</var>, return the complex result <var>x</var><code> + 0i</code>. With 2 real arguments, return the complex result <var>re</var><code> + </code><var>im</var>. <code>complex</code> can often be more convenient than expressions such as <code>a + i*b</code>. For example: <pre class="example"> complex ([1, 2], [3, 4]) ⇒ 1 + 3i 2 + 4i </pre> <!-- Texinfo @sp should work but in practice produces ugly results for HTML. --> <!-- A simple blank line produces the correct behavior. --> <!-- @sp 1 --> <p class="noindent"><strong>See also:</strong> <a href="doc_002dreal.html#doc_002dreal">real</a>, <a href="doc_002dimag.html#doc_002dimag">imag</a>, <a href="doc_002discomplex.html#doc_002discomplex">iscomplex</a>. </p></blockquote></div> <ul class="menu"> <li><a accesskey="1" href="Matrices.html#Matrices">Matrices</a> <li><a accesskey="2" href="Ranges.html#Ranges">Ranges</a> <li><a accesskey="3" href="Single-Precision-Data-Types.html#Single-Precision-Data-Types">Single Precision Data Types</a> <li><a accesskey="4" href="Integer-Data-Types.html#Integer-Data-Types">Integer Data Types</a> <li><a accesskey="5" href="Bit-Manipulations.html#Bit-Manipulations">Bit Manipulations</a> <li><a accesskey="6" href="Logical-Values.html#Logical-Values">Logical Values</a> <li><a accesskey="7" href="Promotion-and-Demotion-of-Data-Types.html#Promotion-and-Demotion-of-Data-Types">Promotion and Demotion of Data Types</a> <li><a accesskey="8" href="Predicates-for-Numeric-Objects.html#Predicates-for-Numeric-Objects">Predicates for Numeric Objects</a> </ul> </body></html>