Hi Dave, I was able to build a pure C++ project using same libraries and it
linked and executed fine, so I assumed boost was ok (yes, I built boost
from src on my system). However, linking the same using cgo is giving these
errors.
On Wednesday, April 20, 2016 at 7:06:28 PM UTC-7, Dorival Pedroso wrote:
>
> Hi,
>
> I'm just wondering what is the cause of the following error (multiple
> definition of __something)?
> C:\Go\pkg\tool\windows_amd64\link.exe: running gcc failed: exit status 1
> C:/TDM-GCC-64/bin/../lib/gcc/x86_64-w64-mingw32/5.1.0/../../../../x86_64-w64-mingw32/lib/../lib/libntdll.a(dyyls01966.o):(.idata$5+0x0):
>
> multiple definition of `__imp_pow'
>
> This only happens on Windows10 but on Ubuntu/Linux.
>
> The Go code makes a call to LAPACK via a C interface as follows:
> package main
>
> /*
> #cgo CFLAGS: -O3
> #cgo linux LDFLAGS: -lm -llapack -lgfortran -lblas
> #cgo windows LDFLAGS: -lm -llapack -lgfortran -lblas -LC:/GoslDeps/lib
>
> #include <stdlib.h>
>
> void dgesvd_(const char* jobu, const char* jobvt, const int* M, const int*
> N, double* A, const int* lda, double* S, double* U, const int* ldu, double*
> VT, const int* ldvt, double* work,const int* lwork, const int* info);
>
> int lapack_svd(double *U, double *S, double *Vt, long m_long, double *A) {
> int m = (int)(m_long);
> int info = 0;
> char job = 'A';
> int lwork = 10*m;
> double* work = (double*)malloc(lwork*sizeof(double));
> dgesvd_(&job, // JOBU
> &job, // JOBVT
> &m, // M
> &m, // N
> A, // A
> &m, // LDA
> S, // S
> U, // U
> &m, // LDU
> Vt, // VT
> &m, // LDVT
> work, // WORK
> &lwork, // LWORK
> &info); // INFO
> free(work);
> return info;
> }
> */
> import "C"
>
> import (
> "fmt"
> "math"
> "unsafe"
> )
>
> func main() {
> A := []float64{1, 2, 3, 2, -4, -9, 3, 6, -3} // col-major format
> m := int(math.Sqrt(float64(len(A))))
> I := func(i, j int) int { return j*m + i }
> printmat(m, A, "A")
> U := make([]float64, len(A))
> S := make([]float64, len(A))
> Vt := make([]float64, len(A))
> info := C.lapack_svd(
> (*C.double)(unsafe.Pointer(&U[0])),
> (*C.double)(unsafe.Pointer(&S[0])),
> (*C.double)(unsafe.Pointer(&Vt[0])),
> (C.long)(m),
> (*C.double)(unsafe.Pointer(&A[0])),
> )
> fmt.Printf("SVD: info = %d\n", info)
> USVt := make([]float64, len(A))
> for i := 0; i < m; i++ {
> for j := 0; j < m; j++ {
> for k := 0; k < m; k++ {
> USVt[I(i, j)] += U[I(i, k)] * S[k] * Vt[I(k, j)]
> }
> }
> }
> printmat(m, USVt, "U*S*Vt")
> }
>
> func printmat(m int, M []float64, msg string) {
> fmt.Printf("%s =\n", msg)
> for i := 0; i < m; i++ {
> for j := 0; j < m; j++ {
> fmt.Printf("%13.8f", M[j*m+i])
> }
> fmt.Println()
> }
> }
>
> Any help is much appreciated.
>
> Cheers.
> Dorival
>
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