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<title>The GNU Fortran Compiler: DOT_PRODUCT</title>
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<a name="DOT_005fPRODUCT"></a>
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Next: <a href="DPROD.html#DPROD" accesskey="n" rel="next">DPROD</a>, Previous: <a href="DIM.html#DIM" accesskey="p" rel="prev">DIM</a>, Up: <a href="Intrinsic-Procedures.html#Intrinsic-Procedures" accesskey="u" rel="up">Intrinsic Procedures</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
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<a name="DOT_005fPRODUCT-_002d_002d_002d-Dot-product-function"></a>
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<h3 class="section">9.80 <code>DOT_PRODUCT</code> — Dot product function</h3>
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<a name="index-DOT_005fPRODUCT"></a>
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<a name="index-dot-product"></a>
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<a name="index-vector-product"></a>
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<a name="index-product_002c-vector"></a>
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<dl compact="compact">
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<dt><em>Description</em>:</dt>
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<dd><p><code>DOT_PRODUCT(VECTOR_A, VECTOR_B)</code> computes the dot product multiplication
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of two vectors <var>VECTOR_A</var> and <var>VECTOR_B</var>. The two vectors may be
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either numeric or logical and must be arrays of rank one and of equal size. If
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the vectors are <code>INTEGER</code> or <code>REAL</code>, the result is
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<code>SUM(VECTOR_A*VECTOR_B)</code>. If the vectors are <code>COMPLEX</code>, the result
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is <code>SUM(CONJG(VECTOR_A)*VECTOR_B)</code>. If the vectors are <code>LOGICAL</code>,
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the result is <code>ANY(VECTOR_A .AND. VECTOR_B)</code>.
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</p>
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</dd>
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<dt><em>Standard</em>:</dt>
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<dd><p>Fortran 95 and later
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</p>
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</dd>
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<dt><em>Class</em>:</dt>
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<dd><p>Transformational function
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</p>
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</dd>
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<dt><em>Syntax</em>:</dt>
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<dd><p><code>RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)</code>
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</p>
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</dd>
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<dt><em>Arguments</em>:</dt>
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<dd><table>
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<tr><td width="15%"><var>VECTOR_A</var></td><td width="70%">The type shall be numeric or <code>LOGICAL</code>, rank 1.</td></tr>
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<tr><td width="15%"><var>VECTOR_B</var></td><td width="70%">The type shall be numeric if <var>VECTOR_A</var> is of numeric type or <code>LOGICAL</code> if <var>VECTOR_A</var> is of type <code>LOGICAL</code>. <var>VECTOR_B</var> shall be a rank-one array.</td></tr>
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</table>
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</dd>
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<dt><em>Return value</em>:</dt>
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<dd><p>If the arguments are numeric, the return value is a scalar of numeric type,
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<code>INTEGER</code>, <code>REAL</code>, or <code>COMPLEX</code>. If the arguments are
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<code>LOGICAL</code>, the return value is <code>.TRUE.</code> or <code>.FALSE.</code>.
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</p>
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</dd>
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<dt><em>Example</em>:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">program test_dot_prod
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integer, dimension(3) :: a, b
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a = (/ 1, 2, 3 /)
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b = (/ 4, 5, 6 /)
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print '(3i3)', a
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print *
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print '(3i3)', b
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print *
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print *, dot_product(a,b)
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end program test_dot_prod
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</pre></div>
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