Linux system C language calls Lapack, Blas Library

In the use of C programming, often call other software packages, where the Lapack,blas library is the most commonly used two libraries, here is the Linux system, the C language programming how to call these two libraries:

1. Let's start with the call to the Blas library, with two vector internal product functions as an example:

#include <stdio.h>#include<math.h>DoubleDdot_ (int*,Double*,int*,Double*,int*);intMain () {intn=2, incx=1, incy=1; Doublex[2]={1.0,1.0}; Doubley[2]={2.0,2.0}; Doublere; Re=ddot_ (&n, X, &incx, Y, &incy); printf ("The result is:%f\n", re); return 0;}

Compile the build target file:

Gcc-c Testddot.c-o TESTDDOT.O

To generate an executable file:

Gcc-o Testddot Testddot.o-lblas-lgfortran   

Get results:

is:4.000000

Note: The Blas library is written in Gfortran, so you need to use the Gfortran library to generate the executable file, and need to link Blas library path, because I put the Blas library in the system default path, so here only need-lblas, otherwise, The path to the Blas library needs to be written out.

2. The following is a Lapack library call method, here to solve the linear equation group as an example.

#include <stdio.h>#include"lapacke.h"#defineM 2#defineN 2intMain () {intI, J, N=n, m=M; intinfo, ipiv[n]; DoubleA[m * n]= {1,2,4,2}; DoubleB[m*n] = {5,4,2.5,2}; Dgesv_ (&n, &n, A, &n, Ipiv, B, &n, &info);  for(j=0; j<2*n; j + +) printf ("%f\t", B[j]); printf ("\ n"); return 0;}

Compile the build target file:

Gcc-o test_dgesv.o-c test_dgesv.c

To generate an executable file:

gcc-  o test_dgesv test_dgesv.o  -llapack  -lblas  

To run the program:

./TEST_DGESV

The results are as follows:

1.000000    1.000000    0.500000    0.500000

Note: The code in Blas and Lapack is written in Fortran, and the matrix in Fortran is stored by column, while the matrix in c is stored by row. Make sure you remember that when you're programmed.

Linux system C language calls Lapack, Blas Library