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<title>Multimin Stopping Criteria - GNU Scientific Library -- Reference Manual</title>
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<h3 class="section">35.6 Stopping Criteria</h3>
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<p>A minimization procedure should stop when one of the following
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<li>A minimum has been found to within the user-specified precision.
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<li>A user-specified maximum number of iterations has been reached.
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<li>An error has occurred.
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<p class="noindent">The handling of these conditions is under user control. The functions
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below allow the user to test the precision of the current result.
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— Function: int <b>gsl_multimin_test_gradient</b> (<var>const gsl_vector * g, double epsabs</var>)<var><a name="index-gsl_005fmultimin_005ftest_005fgradient-2238"></a></var><br>
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<blockquote><p>This function tests the norm of the gradient <var>g</var> against the
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absolute tolerance <var>epsabs</var>. The gradient of a multidimensional
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function goes to zero at a minimum. The test returns <code>GSL_SUCCESS</code>
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if the following condition is achieved,
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and returns <code>GSL_CONTINUE</code> otherwise. A suitable choice of
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<var>epsabs</var> can be made from the desired accuracy in the function for
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small variations in x. The relationship between these quantities
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is given by <!-- {$\delta{f} = g\,\delta{x}$} -->
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\delta f = g \delta x.
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</p></blockquote></div>
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— Function: int <b>gsl_multimin_test_size</b> (<var>const double size, double epsabs</var>)<var><a name="index-gsl_005fmultimin_005ftest_005fsize-2239"></a></var><br>
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<blockquote><p>This function tests the minimizer specific characteristic
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size (if applicable to the used minimizer) against absolute tolerance <var>epsabs</var>.
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The test returns <code>GSL_SUCCESS</code> if the size is smaller than tolerance,
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otherwise <code>GSL_CONTINUE</code> is returned.
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</p></blockquote></div>
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