func dgesddHelper(m, n int, a []float64, lda int, s, u []float64, ldu int, vt []float64, ldvt int, work []float64, lwork int, iwork []C.integer) error {
var (
jobz_ = C.char('S')
m_ = C.integer(m)
n_ = C.integer(n)
a_ = ptrFloat64(a)
lda_ = C.integer(lda)
s_ = ptrFloat64(s)
u_ = ptrFloat64(u)
ldu_ = C.integer(ldu)
vt_ = ptrFloat64(vt)
ldvt_ = C.integer(ldvt)
work_ = ptrFloat64(work)
lwork_ = C.integer(lwork)
iwork_ = ptrInt(iwork)
)
var info_ C.integer
C.dgesdd_(&jobz_, &m_, &n_, a_, &lda_, s_, u_, &ldu_, vt_, &ldvt_, work_, &lwork_, iwork_, &info_)
info := int(info_)
switch {
case info < 0:
return errInvalidArg(-info)
case info > 0:
return errFailConverge(info)
default:
return nil
}
}
func Dgesdd(jobz string, M, N int, A []float64, lda int, S []float64, U []float64,
ldu int, Vt []float64, ldvt int) int {
var info int = 0
var lwork int = -1
var work float64
cjobz := C.CString(jobz)
defer C.free(unsafe.Pointer(cjobz))
iwork := make([]int, 8*min(M, N))
// pre-calculate work buffer size
C.dgesdd_(cjobz, (*C.int)(unsafe.Pointer(&M)), (*C.int)(unsafe.Pointer(&N)),
nil, (*C.int)(unsafe.Pointer(&lda)),
nil, nil, (*C.int)(unsafe.Pointer(&ldu)),
nil, (*C.int)(unsafe.Pointer(&ldvt)),
(*C.double)(unsafe.Pointer(&work)), (*C.int)(unsafe.Pointer(&lwork)),
(*C.int)(unsafe.Pointer(&iwork[0])),
(*C.int)(unsafe.Pointer(&info)))
// allocate work area
lwork = int(work)
wbuf := make([]float64, lwork)
var Ubuf, Vtbuf *C.double
if U != nil {
Ubuf = (*C.double)(unsafe.Pointer(&U[0]))
} else {
Ubuf = (*C.double)(unsafe.Pointer(nil))
}
if Vt != nil {
Vtbuf = (*C.double)(unsafe.Pointer(&Vt[0]))
} else {
Vtbuf = (*C.double)(unsafe.Pointer(nil))
}
C.dgesdd_(cjobz, (*C.int)(unsafe.Pointer(&M)), (*C.int)(unsafe.Pointer(&N)),
(*C.double)(unsafe.Pointer(&A[0])), (*C.int)(unsafe.Pointer(&lda)),
(*C.double)(unsafe.Pointer(&S[0])), Ubuf, (*C.int)(unsafe.Pointer(&ldu)),
Vtbuf, (*C.int)(unsafe.Pointer(&ldvt)),
(*C.double)(unsafe.Pointer(&wbuf[0])), (*C.int)(unsafe.Pointer(&lwork)),
(*C.int)(unsafe.Pointer(&iwork[0])),
(*C.int)(unsafe.Pointer(&info)))
return info
}