undefined reference to `dgemm_' in gfortran in windows subsystem ubuntu - gfortran

Question

I have the following Fortran code from https://software.intel.com/content/www/us/en/develop/documentation/mkl-tutorial-fortran/top/multiplying-matrices-using-dgemm.html
I am trying to use gfortran complile it (named as dgemm.f90)
! Fortran source code is found in dgemm_example.f
PROGRAM MAIN
IMPLICIT NONE
DOUBLE PRECISION ALPHA, BETA
INTEGER M, K, N, I, J
PARAMETER (M=2000, K=200, N=1000)
DOUBLE PRECISION A(M,K), B(K,N), C(M,N)
PRINT *, "This example computes real matrix C=alpha*A*B+beta*C"
PRINT *, "using Intel(R) MKL function dgemm, where A, B, and C"
PRINT *, "are matrices and alpha and beta are double precision "
PRINT *, "scalars"
PRINT *, ""
PRINT *, "Initializing data for matrix multiplication C=A*B for "
PRINT 10, " matrix A(",M," x",K, ") and matrix B(", K," x", N, ")"
10 FORMAT(a,I5,a,I5,a,I5,a,I5,a)
PRINT *, ""
ALPHA = 1.0
BETA = 0.0
PRINT *, "Intializing matrix data"
PRINT *, ""
DO I = 1, M
DO J = 1, K
A(I,J) = (I-1) * K + J
END DO
END DO
DO I = 1, K
DO J = 1, N
B(I,J) = -((I-1) * N + J)
END DO
END DO
DO I = 1, M
DO J = 1, N
C(I,J) = 0.0
END DO
END DO
PRINT *, "Computing matrix product using Intel(R) MKL DGEMM "
PRINT *, "subroutine"
CALL DGEMM('N','N',M,N,K,ALPHA,A,M,B,K,BETA,C,M)
PRINT *, "Computations completed."
PRINT *, ""
PRINT *, "Top left corner of matrix A:"
PRINT 20, ((A(I,J), J = 1,MIN(K,6)), I = 1,MIN(M,6))
PRINT *, ""
PRINT *, "Top left corner of matrix B:"
PRINT 20, ((B(I,J),J = 1,MIN(N,6)), I = 1,MIN(K,6))
PRINT *, ""
20 FORMAT(6(F12.0,1x))
PRINT *, "Top left corner of matrix C:"
PRINT 30, ((C(I,J), J = 1,MIN(N,6)), I = 1,MIN(M,6))
PRINT *, ""
30 FORMAT(6(ES12.4,1x))
PRINT *, "Example completed."
STOP
END
By gfortran -lblas -llapack dgemm.f90, I got
/tmp/ccUtHQz1.o: In function `MAIN__':
dgemm.f90:(.text+0x794): undefined reference to `dgemm_'
collect2: error: ld returned 1 exit status
I searched that this type of question has been asked time to time, but I haven't found a solution for my case :(
I tried to use python load blas, based on https://software.intel.com/content/www/us/en/develop/articles/using-intel-mkl-in-your-python-programs.html
from ctypes import *
mkl = cdll.LoadLibrary("./anaconda3/lib/libmkl_rt.so")
dgemm = mkl.cblas_dgemm
def print_mat(mat, m, n):
for i in xrange(0,m):
print " ",
for j in xrange(0,n):
print mat[i*n+j],
print
Order = 101 # 101 for row-major, 102 for column major data structures
TransA = 111 # 111 for no transpose, 112 for transpose, and 113 for conjugate transpose
TransB = 111
m = 2
n = 4
k = 3
lda = k
ldb = n
ldc = n
alpha = 1.0
beta = -1.0
amat = c_double * 6
bmat = c_double * 12
cmat = c_double * 8
a = amat(1,2,3, 4,5,6)
b = bmat(0,1,0,1, 1,0,0,1, 1,0,1,0)
c = cmat(5,1,3,3, 11,4,6,9)
print "\nMatrix A ="
print_mat(a,2,3)
print "\nMatrix B ="
print_mat(b,3,4)
print "\nMatrix C ="
print_mat(c,2,4)
print "\nCompute", alpha, "* A * B + ", beta, "* C"
dgemm( c_int(Order), c_int(TransA), c_int(TransB), c_int(m), c_int(n), c_int(k), c_double(alpha), byref(a), c_int(lda), byref(b), c_int(ldb), c_double(beta), byref(c), c_int(ldc))
print_mat(c,2,4)
print
The above code works. Hence, the question may be related to use mkl with gfortran?

Answer 1

You should follow Intel's website to set the compiler flags for gfortran + MKL. Otherwise your will be linking with something else.
https://software.intel.com/content/www/us/en/develop/tools/oneapi/components/onemkl/link-line-advisor.html