[Help-gsl] How to calculate integral of a b-spline?

[Iryna Feuerstein]

Hello,

I need to calculate an integral of the following type:

\int f(x)*B(i,k)(x) dx,

where B(i,k) is a basis spline of the degree k  with a De Boor point i.

I took a look at gls numerical integration functions, and I've already 
used the gsl basis splines. But I have no idea, if the construction of 
the above-mentioned integral is possible with the gsl functions.

The computation of the b-spline functions requires a 
gsl_bspline_workspace. I know, that it is possible to calculate the 
values of all allocated b-splines at the point x with the function 
gsl_bspline_eval, but is there some way to extract the i-th b-spline as 
a function from the bspline_workspace, so that I could use it for the 
integration?

Could somebody please help me with this problem?

Yours faithfully,
Iryna.