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<h3 class="section">8.63 <code>DOT_PRODUCT</code> — Dot product function</h3>
<p><a name="index-DOT_005fPRODUCT-552"></a><a name="index-dot-product-553"></a><a name="index-vector-product-554"></a><a name="index-product_002c-vector-555"></a>
<dl>
<dt><em>Description</em>:<dd><code>DOT_PRODUCT(VECTOR_A, VECTOR_B)</code> computes the dot product multiplication
of two vectors <var>VECTOR_A</var> and <var>VECTOR_B</var>. The two vectors may be
either numeric or logical and must be arrays of rank one and of equal size. If
the vectors are <code>INTEGER</code> or <code>REAL</code>, the result is
<code>SUM(VECTOR_A*VECTOR_B)</code>. If the vectors are <code>COMPLEX</code>, the result
is <code>SUM(CONJG(VECTOR_A)*VECTOR_B)</code>. If the vectors are <code>LOGICAL</code>,
the result is <code>ANY(VECTOR_A .AND. VECTOR_B)</code>.
<br><dt><em>Standard</em>:<dd>Fortran 95 and later
<br><dt><em>Class</em>:<dd>Transformational function
<br><dt><em>Syntax</em>:<dd><code>RESULT = DOT_PRODUCT(VECTOR_A, VECTOR_B)</code>
<br><dt><em>Arguments</em>:<dd>
<p><table summary=""><tr align="left"><td valign="top" width="15%"><var>VECTOR_A</var> </td><td valign="top" width="70%">The type shall be numeric or <code>LOGICAL</code>, rank 1.
<br></td></tr><tr align="left"><td valign="top" width="15%"><var>VECTOR_B</var> </td><td valign="top" 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.
<br></td></tr></table>
<br><dt><em>Return value</em>:<dd>If the arguments are numeric, the return value is a scalar of numeric type,
<code>INTEGER</code>, <code>REAL</code>, or <code>COMPLEX</code>. If the arguments are
<code>LOGICAL</code>, the return value is <code>.TRUE.</code> or <code>.FALSE.</code>.
<br><dt><em>Example</em>:<dd>
<pre class="smallexample"> program test_dot_prod
integer, dimension(3) :: a, b
a = (/ 1, 2, 3 /)
b = (/ 4, 5, 6 /)
print '(3i3)', a
print *
print '(3i3)', b
print *
print *, dot_product(a,b)
end program test_dot_prod
</pre>
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