Well, I don't know Perl, but I do know GSL. Statemens in your code are in a wrong order. 1) Allocate 6 bins gsl_histogram* h=gsl_histogram_alloc(6); 2) Set the ranges. 6 bins require 7 points. (you have 6) double ranges7={1.,2.,3.,4.,5.,6.,7.}; gsl_histogram_set_ranges(h,ranges,7); 3) And only after initialization one can use the histogram 4) In C one should free the histogram after using it. No idea about Perl.