The Complete SPRLIB & ANNLIB

sammon_dstress

- calculate the derivative of Sammon's stress measure

SYNOPSIS

int sammon_stress (i, dE, d2E)

ARGUMENTS

int i The sample number for which the derivative has to be calculated.
double *dE A vector of map_dim elements (see SAMMON-VARIABLES) in which the derivative of Sammon's stress measure w.r.t. sample i is returned. The vector starts at element 0.
double *d2E A vector of the same length in which the second derivative w.r.t. sample i is returned.

RETURNS

TRUE in case an error occured, FALSE otherwise.

FUNCTION

This function calculates the first and second derivative of Sammon's stress between an original dataset and its Sammon mapping with respect to a certain sample i. It is used by sammon_solve in the gradient descent algorithm.

SEE ALSO

sammon_solve, sammon_stress

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