void invspline1D(double *c, int size, double *z, int npoles)
{
double lambda;
int n, k;
/* normalization */
for (k = npoles, lambda = 1.; k--;)
lambda *= (1. - z[k]) * (1. - 1. / z[k]);
for (n = size; n--;)
c[n] *= lambda;
/*----- Loop on poles -----*/
for (k = 0; k < npoles; k++) {
/* forward recursion */
c[0] = initcausal(c, size, z[k]);
for (n = 1; n < size; n++)
c[n] += z[k] * c[n - 1];
/* backwards recursion */
c[size - 1] = initanticausal(c, size, z[k]);
for (n = size - 1; n--;)
c[n] = z[k] * (c[n + 1] - c[n]);
}
}
static void invspline1D(float *c, int step, int size, double *z, int npoles)
{
/* normalization */
double lambda=1;
for (int k = npoles-1; k >= 0; k--)
lambda *= (1-z[k])*(1-1/z[k]);
for (int n = size-1; n >= 0; n--)
c[step*n] *= lambda;
for (int k = 0 ; k < npoles; k++) { // Loop on poles
/* forward recursion */
c[0] = initcausal(c, step, size, z[k]);
for (int n = 1; n < size; n++)
c[step*n] += z[k]*c[step*(n-1)];
/* backward recursion */
c[step*(size-1)] = initanticausal(c, step, size, z[k]);
for (int n = size-2; n >= 0; n--)
c[step*n] = z[k]*(c[step*(n+1)]-c[step*n]);
}
}
