LAPACK problems

[Dave Mazzoni]

Hi all - I'm trying to get go running with the OpenBLAS library. I just installed 1.8rc1 in case it matters. Here is what I'm doing:

go get -u github.com/gonum/lapack/...

After several seconds, I get many errors of this sort:

...

/tmp/go-build240658416/github.com/gonum/lapack/cgo/lapacke/_obj/lapacke.cgo2.o: In function `_cgo_8ea242716dd6_Cfunc_LAPACKE_zupgtr_work':

gonum/lapack/cgo/lapacke/cgo-gcc-prolog:32780: undefined reference to `LAPACKE_zupgtr_work'

/tmp/go-build240658416/github.com/gonum/lapack/cgo/lapacke/_obj/lapacke.cgo2.o: In function `_cgo_8ea242716dd6_Cfunc_LAPACKE_zupmtr_work':

gonum/lapack/cgo/lapacke/cgo-gcc-prolog:32810: undefined reference to `LAPACKE_zupmtr_work'

collect2: error: ld returned 1 exit status

What am I doing wrong?

Dave

[Dave Mazzoni]

 I was not RTFMing. After reading and executing the install as specified in the README.md, this works:

CGO_LDFLAGS="-L/opt/Downloads/OpenBLAS -lopenblas" go get -u github.com/gonum/lapack

without any errors.

Is it necessary to go into each of the gonum component directories and do, for example CGO_LDFLAGS="-L/path/to/OpenBLAS -lopenblas" go install github.com/gonum/lapack/cgo ?

[Dave Mazzoni]

Now I'm having trouble with clapack. I've installed it properly, but at compile time I get this:

 CGO_LDFLAGS="-L/opt/Downloads/OpenBLAS -lopenblas" go build cgeev.go

cgeev.go:10:2: cannot find package "github.com/gonum/lapack/cgo/clapack" in any of:

/usr/local/go/src/github.com/gonum/lapack/cgo/clapack (from $GOROOT)

/opt/Projects/Golang/src/github.com/gonum/lapack/cgo/clapack (from $GOPATH)

Has something changed with lapack? This used to work...

On Friday, January 13, 2017 at 12:35:38 PM UTC-5, Dave Mazzoni wrote:

[Brendan Tracey]

Do you have a reproducer? That seems like a Go error, not a C one.

From what I understand, the compilation knows the value of CGO_LDFLAGS, so if you want to change that value, you have to recompile.

[Vladimír Chalupecký]

We renamed the clapack package to lapacke some time ago. I guess that renaming the import path in your could will fix the issue.

[Dave Mazzoni]

That was it!  Here's my code:

--------------------------------------

// Simple Eigenvalue calculation using LAPACK/CGO functions

// Built with:

// CGO_LDFLAGS="-L/opt/Downloads/OpenBLAS -lopenblas" go build cgeev.go

package main

import (

"fmt"

"github.com/gonum/lapack"

"github.com/gonum/lapack/cgo/lapacke"

)

func main() {

jobvl := lapack.Job('V')

jobvr := lapack.Job('V')

n, lda, ldvl, lvdr, lwork := 2, 2, 2, 2, 4

a := []complex128{1 + 1i, 2 - 1i, 2 + 1i, 1 - 1i}

showMatrix("Working matrix:", a)

w := make([]complex128, 2)

vl := make([]complex128, 4)

vr := make([]complex128, 4)

work := make([]complex128, 4)

rwork := make([]float64, 4)

lapacke.Zgeev(jobvl, jobvr, n, a, lda, w, vl, ldvl, vr, lvdr,

work, lwork, rwork)

showMatrix("Left Eigenvectors:", vl)

showMatrix("Right Eigenvectors:", vr)

showMatrix("Eigenvalues:", w)

}

func showMatrix(label string, m []complex128) {

fmt.Printf("\n%s:\n", label)

for i := range m {

fmt.Printf("%4.2f\t", m[i])

if i%2 != 0 {

fmt.Printf("\n")

}

}

}

---------------------------------------

go build zgeev.go  (runs without any errors and produces zgeev executable)

./zgeev

Working matrix::

(1.00+1.00i) (2.00-1.00i)

(2.00+1.00i) (1.00-1.00i)

Left Eigenvectors::

(0.71+0.00i) (0.71+0.00i)

(0.42+0.57i) (-0.71-0.00i)

Right Eigenvectors::

(0.71-0.00i) (0.71+0.00i)

(0.71+0.00i) (-0.42-0.57i)

Eigenvalues::

(3.00-0.00i) (-1.00+0.00i)

Thanks for the help!

Dave