NumCosmoXcorKernelIntegrandset_residuals

Records the residual the fit achieved on each knot interval, one row per knot of nc_xcor_kernel_integrand_peek_knots() and one column per component, as produced by ncm_function_sample_set_get_residuals().

This is the sharper half of the pair with nc_xcor_kernel_integrand_set_tolerances(): the tolerances say what the fit was asked for, and refinement beats its own request by orders — by 12 to 3100 depending on the kernel, which is enough for an error built from the tolerances alone to be unable to tell a well-fitted pair from a badly fitted one. Where these residuals are present NC_XCOR_METHOD_KERNEL_EXACT uses them and falls back to the tolerances only on intervals that carry no record (NaN). See nc_xcor_compute_full().