Compiler error C2664 on 64 bit platform

Question

I have a program that compiles and runs using win 32 platform in Visual Studio 2012. After changing the platform to X64, it gives the following error message:

" test_integration.cpp(27): error C2664: 'hcubature_v' : cannot convert parameter 2 from 'int (__cdecl *)(unsigned int,unsigned int,const double *,void *,unsigned int,double *)' to 'integrand_v' "

Could anyone offer some suggestions? Thank you!

#include <iostream>
#include "cubature.h"
#include <ctime>
#include <limits>
using namespace std;

int f_v(unsigned ndim, unsigned npts, const double *x, void *fdata, unsigned fdim, double *fval) {
    double sigma = *((double *) fdata);
    unsigned i, j;
    for (j = 0; j < npts; ++j) { // evaluate the integrand for npts points
        double sum = 0;
        for (i = 0; i < ndim; ++i) sum += x[j*ndim+i] * x[j*ndim+i];
        fval[j] = exp(-sigma * sum);
    };
    return 0; // success
}

int main(){

    double xmin[3] = {-2,-2,-2}, xmax[3] = {2,2,2}, sigma = 0.5;
    double  val_v,err_v, time_v;
    const clock_t begin_time_v = clock();

    for (int j = 0; j<1000;j++)
    {
    // hcubature_v calculates a multidimensional integration.
    hcubature_v(1, f_v, &sigma, 1, xmin, xmax, 0, 0, 1e-4, ERROR_INDIVIDUAL, &val_v, &err_v);
    }

    cout << float( clock () - begin_time_v ) /  CLOCKS_PER_SEC<<endl;
    printf("Computed integral   = %0.10g +/- %g\n", val_v, err_v);
    cin.get();
}

Here are some additional definitions:

/* a vector integrand of a vector of npt points: x[i*ndim + j] is the
   j-th coordinate of the i-th point, and the k-th function evaluation
   for the i-th point is returned in fval[i*fdim + k].  Return 0 on success
   or nonzero to terminate the integration. */
typedef int (*integrand_v) (unsigned ndim, size_t npt,
                const double *x, void *,
                unsigned fdim, double *fval);

/* as hcubature, but vectorized integrand */
int hcubature_v(unsigned fdim, integrand_v f, void *fdata,
        unsigned dim, const double *xmin, const double *xmax, 
        size_t maxEval, double reqAbsError, double reqRelError, 
        error_norm norm,
        double *val, double *err);

Answer 1

You should use the exact types that are used to define integrand_v.

Instead of:

int f_v(unsigned ndim, unsigned npts, const double *x, void *fdata, unsigned fdim, double *fval) {
                       ^^^^^^

Use

int f_v(unsigned ndim, size_t npt,  const double *x, void *fdata, unsigned fdim, double *fval) {
                       ^^^^^^

It works in 32 bit probably because size_t and unsigned happen to be the same type.

It does not work in 64 bit since they are different types.