This function evaluates the metric of a certain basis. The metric is the inprod of the basis functions.
Examples
basis = create_bspline_basis(start=0, end=10, nbasis=10, norder=4)
metric = evaluate_metric(basis)
basis1 = create_bspline_basis(start=0, end=20, nbasis=10, norder=1)
metric1 = evaluate_metric(basis1)
