# Using lapack in fortran programs

**URL:** <https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56>\
**Category:** Help\
**Created:** [May 21, 2020, 7:12pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56 "2020-05-21T19:12:39Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ELNS](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/elns/32/3338_2.png) [@ELNS](https://fortran-lang.discourse.group/u/ELNS)\
**Post date:** [May 21, 2020, 7:12pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/1 "2020-05-21T19:12:39Z")

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Hi all  
I have installed lapack library in my linux system using both pacman package manager and conda, but when i wanted to use its subroutines in my fortran programs i got error below:

`$ gfortran test.f90`

> /home/linuxbrew/.linuxbrew/bin/ld: /tmp/ccmmwhkj.o: in function `MAIN__': test.f90:(.text+0xdb): undefined reference to `sgesv\_’  
> collect2: error: ld returned 1 exit status

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**Author:** ![certik](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/certik/32/4_2.png) [@certik](https://fortran-lang.discourse.group/u/certik)\
**Post date:** [May 21, 2020, 7:20pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/2 "2020-05-21T19:20:42Z")

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Hi @ELNS, you have to link against lapack such as

```auto
gfortran test.f90 -llapack

```

In the future, our Fortran Package Manger (fpm) will be able to do this for you, but for now you have to do it manually one way or another.

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<div class="post-metadata">

**Author:** ![ELNS](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/elns/32/3338_2.png) [@ELNS](https://fortran-lang.discourse.group/u/ELNS)\
**Post date:** [May 21, 2020, 7:35pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/3 "2020-05-21T19:35:24Z")

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I have another question:  
Should i mention all used libraries in your suggested command?  
For example : `$ gfortran test.f90 -l lapack blas`

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**Author:** ![certik](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/certik/32/4_2.png) [@certik](https://fortran-lang.discourse.group/u/certik)\
**Post date:** [May 21, 2020, 7:44pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/4 "2020-05-21T19:44:17Z")

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That depends on your Lapack installation. The syntax is `-llapack -lblas`.

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<div class="post-metadata">

**Author:** ![ELNS](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/elns/32/3338_2.png) [@ELNS](https://fortran-lang.discourse.group/u/ELNS)\
**Post date:** [May 21, 2020, 7:45pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/5 "2020-05-21T19:45:10Z")

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Thank you very mush 🙏 🙏 🙏  
I am so glad that i am here.

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**Author:** ![certik](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/certik/32/4_2.png) [@certik](https://fortran-lang.discourse.group/u/certik)\
**Post date:** [May 21, 2020, 7:56pm UTC](https://fortran-lang.discourse.group/t/using-lapack-in-fortran-programs/56/6 "2020-05-21T19:56:38Z")

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We are happy to have you here!