public static int ContractByBest(nmsimplex_state_t state, int best, PZMath_vector xc,
PZMath_multimin_function f)
{
/* Function contracts the simplex in respect to
best valued corner. That is, all corners besides the
best corner are moved. */
/* the xc vector is simply work space here */
PZMath_matrix x1 = state.x1;
PZMath_vector y1 = state.y1;
int i, j;
double newval;
for (i = 0; i < x1.RowCount; i++)
{
if (i != best)
{
for (j = 0; j < x1.ColumnCount; j++)
{
newval = 0.5 * (x1[i, j] + x1[best, j]);
x1[i, j] = newval;
}
/* evaluate function in the new point */
x1.CopyRow2(i, xc);
newval = f.FN_EVAL(xc);
y1[i] = newval;
}
}
return PZMath_errno.PZMath_SUCCESS;
}
public static int Init(object vstate, PZMath_multimin_function f, PZMath_vector x,
out double size, PZMath_vector step_size)
{
int i;
double val;
PZMath_vector xtemp = (vstate as nmsimplex_state_t).ws1;
/* first point is the original x0 */
val = f.FN_EVAL(x);
(vstate as nmsimplex_state_t).x1.SetRow(0, x);
(vstate as nmsimplex_state_t).y1[0] = val;
/* following points are initialized to x0 + step_size */
for (i = 0; i < x.size; i++)
{
xtemp.MemCopyFrom(x);
val = xtemp[i] + step_size[i];
xtemp[i] = val;
val = f.FN_EVAL(xtemp);
(vstate as nmsimplex_state_t).x1.SetRow(i + 1, xtemp);
(vstate as nmsimplex_state_t).y1[i + 1] = val;
}
/* Initialize simplex size */
size = Size (vstate as nmsimplex_state_t);
return PZMath_errno.PZMath_SUCCESS;
}
public static double MoveCorner(double coeff, nmsimplex_state_t state, int corner,
PZMath_vector xc, PZMath_multimin_function f)
{
/* moves a simplex corner scaled by coeff (negative value represents
mirroring by the middle point of the "other" corner points)
and gives new corner in xc and function value at xc as a
return value
*/
PZMath_matrix x1 = state.x1;
int i, j;
double newval, mp;
if (x1.RowCount < 2)
{
PZMath_errno.ERROR ("nmsimplex::MoveCorner(), simplex cannot have less than two corners!", PZMath_errno.PZMath_FAILURE);
}
for (j = 0; j < x1.ColumnCount; j++)
{
mp = 0.0;
for (i = 0; i < x1.RowCount; i++)
{
if (i != corner)
{
mp += (x1[i, j]);
}
}
mp /= (double) (x1.RowCount - 1);
newval = mp - coeff * (mp - x1[corner, j]);
xc[j] = newval;
}
newval = f.FN_EVAL(xc);
return newval;
}