GSL积分运算

#include <stdio.h>#include <math.h>#include <gsl/gsl_integration.h>#pragma comment(lib, "libgsl_d.lib")#pragma comment(lib, "libgslcblas_d.lib")double f (double x, void * params) {  double alpha = *(double *) params;  double f = log(alpha*x) / sqrt(x);  return f;}intmain (void){  gsl_integration_workspace * w     = gsl_integration_workspace_alloc (1000);    double result, error;  double expected = -4.0;  double alpha = 1.0;  gsl_function F;  F.function = &f;  F.params = α  gsl_integration_qags (&F, 0, 1, 0, 1e-7, 1000,                        w, &result, &error);   printf ("result          = % .18f\n", result);  printf ("exact result    = % .18f\n", expected);  printf ("estimated error = % .18f\n", error);  printf ("actual error    = % .18f\n", result - expected);  printf ("intervals =  %d\n", w->size);  return 0;}