text: #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <math.h>
  #include <gbpLib.h>
  #include <gbpMath.h>
  #include <gbpCosmo_linear_theory.h>
  
  double k_of_M(double M, cosmo_info *cosmo) {
      double R = R_of_M(M, cosmo);
      double k = k_of_R(R);
      return (k);
  }
  