void
test_bspline(gsl_bspline_workspace * bw, gsl_bspline_deriv_workspace * dbw)
{
gsl_vector *B;
gsl_matrix *dB;
size_t i, j;
size_t n = 100;
size_t ncoeffs = gsl_bspline_ncoeffs(bw);
size_t order = gsl_bspline_order(bw);
size_t nbreak = gsl_bspline_nbreak(bw);
double a = gsl_bspline_breakpoint(0, bw);
double b = gsl_bspline_breakpoint(nbreak - 1, bw);
B = gsl_vector_alloc(ncoeffs);
dB = gsl_matrix_alloc(ncoeffs, 1);
/* Ensure B-splines form a partition of unity */
for (i = 0; i < n; i++)
{
double xi = a + (b - a) * (i / (n - 1.0));
double sum = 0;
gsl_bspline_eval(xi, B, bw);
for (j = 0; j < ncoeffs; j++)
{
double Bj = gsl_vector_get(B, j);
int s = (Bj < 0 || Bj > 1);
gsl_test(s,
"basis-spline coefficient %u is in range [0,1] for x=%g",
j, xi);
sum += Bj;
}
gsl_test_rel(sum, 1.0, order * GSL_DBL_EPSILON,
"basis-spline order %u is normalized for x=%g", order,
xi);
}
/* Ensure B-splines 0th derivatives agree with regular evaluation */
for (i = 0; i < n; i++)
{
double xi = a + (b - a) * (i / (n - 1.0));
gsl_bspline_eval(xi, B, bw);
gsl_bspline_deriv_eval(xi, 0, dB, bw, dbw);
for (j = 0; j < ncoeffs; j++)
{
gsl_test_abs(gsl_matrix_get(dB, j, 0), gsl_vector_get(B, j),
GSL_DBL_EPSILON,
"b-spline order %d basis #%d evaluation and 0th derivative consistent for x=%g",
order, j, xi);
}
}
gsl_vector_free(B);
gsl_matrix_free(dB);
}
/**
* Copy break points from GSL internal objects
* @param bp :: A vector to accept the break points.
*/
void BSpline::getGSLBreakPoints(std::vector<double> &bp) const {
size_t n = gsl_bspline_nbreak(m_bsplineWorkspace.get());
bp.resize(n);
for (size_t i = 0; i < n; ++i) {
bp[i] = gsl_bspline_breakpoint(i, m_bsplineWorkspace.get());
}
}
void
test_bspline (gsl_bspline_workspace * bw)
{
gsl_vector *B;
size_t i, j;
size_t n = 100;
size_t ncoeffs = gsl_bspline_ncoeffs (bw);
size_t order = gsl_bspline_order (bw);
size_t nbreak = gsl_bspline_nbreak (bw);
double a = gsl_bspline_breakpoint (0, bw);
double b = gsl_bspline_breakpoint (nbreak - 1, bw);
B = gsl_vector_alloc (ncoeffs);
for (i = 0; i < n; i++)
{
double xi = a + (b - a) * (i / (n - 1.0));
double sum = 0;
gsl_bspline_eval (xi, B, bw);
for (j = 0; j < ncoeffs; j++)
{
double Bj = gsl_vector_get (B, j);
int s = (Bj < 0 || Bj > 1);
gsl_test (s,
"basis-spline coefficient %u is in range [0,1] for x=%g",
j, xi);
sum += Bj;
}
gsl_test_rel (sum, 1.0, order * GSL_DBL_EPSILON,
"basis-spline order %u is normalized for x=%g", order,
xi);
}
gsl_vector_free (B);
}
static VALUE rb_gsl_bspline_breakpoint(VALUE obj, VALUE i)
{
gsl_bspline_workspace *w;
Data_Get_Struct(obj, gsl_bspline_workspace, w);
return rb_float_new(gsl_bspline_breakpoint(FIX2INT(i), w));
}
