I am on Ubuntu 21.04, using GSL 2.7. Here is my test program norm.c :
#include <stdio.h> #include <gsl/gsl_spmatrix.h> int main() { gsl_spmatrix_uchar *A = gsl_spmatrix_uchar_alloc(2, 2); gsl_spmatrix_uchar_set(A, 0, 0, 1); gsl_spmatrix_uchar_set(A, 0, 1, 2); gsl_spmatrix_uchar_set(A, 1, 0, 3); gsl_spmatrix_uchar_set(A, 1, 1, 4); double norm = gsl_spmatrix_uchar_norm1(A); printf("norm = %g\n", norm); gsl_spmatrix_uchar_free(A); return 0; } When I compile this I get an error message from the linker: $ gcc -Wall -I/opt/gsl/gsl-2.7/include -c norm.c $ gcc -L/opt/gsl/gsl-2.7/lib -o norm norm.o -lgsl -lgslcblas -lm /bin/ld: norm.o: in function `main': norm.c:(.text+0x93): undefined reference to `gsl_spmatrix_uchar_norm1' collect2: error: ld returned 1 exit status Best regards, Håkon Hægland