GNU Scientific Library Reference Manual - Third Edition (v1.12)by M. Galassi, J. Davies, J. Theiler, B. Gough, G. Jungman, P. Alken, M. Booth, F. Rossi Paperback (6"x9"), 592 pages, 60 figures ISBN 0954612078 RRP £24.95 ($39.95) |

## 35.6 Stopping Criteria

A minimization procedure should stop when one of the following conditions is true:

- A minimum has been found to within the user-specified precision.
- A user-specified maximum number of iterations has been reached.
- An error has occurred.

The handling of these conditions is under user control. The functions below allow the user to test the precision of the current result.

__Function:__int**gsl_multimin_test_gradient***(const gsl_vector **`g`, double`epsabs`)- This function tests the norm of the gradient
`g`against the absolute tolerance`epsabs`. The gradient of a multidimensional function goes to zero at a minimum. The test returns`GSL_SUCCESS`

if the following condition is achieved,|g| < epsabs

and returns

`GSL_CONTINUE`

otherwise. A suitable choice of`epsabs`can be made from the desired accuracy in the function for small variations in x. The relationship between these quantities is given by \delta f = g \delta x.

__Function:__int**gsl_multimin_test_size***(const double*`size`, double`epsabs`)- This function tests the minimizer specific characteristic
size (if applicable to the used minimizer) against absolute tolerance
`epsabs`. The test returns`GSL_SUCCESS`

if the size is smaller than tolerance, otherwise`GSL_CONTINUE`

is returned.

ISBN 0954612078 | GNU Scientific Library Reference Manual - Third Edition (v1.12) | See the print edition |