# Some problems occurred in the solution

**URL:** <https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429>\
**Category:** General Discussion\
**Created:** [January 13, 2022, 8:55am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429 "2022-01-13T08:55:41Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 13, 2022, 8:55am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/1 "2022-01-13T08:55:42Z")

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Each time the program runs, the speed is very slow, and the following happens  
Error umpfack umfpack\_zl\_symbolic status -1  
Error umpfack umfpack\_zl\_numeric status -4  
Error umfpack\_di\_solve status -3  
why?

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**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [January 13, 2022, 9:48am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/2 "2022-01-13T09:48:19Z")

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The error is  
#define UMFPACK\_ERROR\_out\_of\_memory (-1)

This is with why it is so slow.

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 13, 2022, 10:04am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/3 "2022-01-13T10:04:43Z")

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Thank you, professor. Is there any solution to this problem?

load “UMFPACK64”;  
…  
problem kg2(psai2,u,solver=“UMFPACK64”)=  
…

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 13, 2022, 10:14am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/4 "2022-01-13T10:14:08Z")

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I can’t tell the cause of the error. Is there a reference book？

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 13, 2022, 10:22am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/5 "2022-01-13T10:22:46Z")

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Using MUMPS,  
load “MUMPS”  
…  
problem kg2(psai2,u,solver=sparsesolver,master=-1)=int2d(Th1)(psai2\*u/(dt^2))

…

why?

– Square mesh : nb vertices =40401 , nb triangles = 80000 , nb boundary edges 800  
– Square mesh : nb vertices =289 , nb triangles = 512 , nb boundary edges 64  
Attempting to use an MPI routine before initializing MPI

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<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [January 13, 2022, 10:52am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/6 "2022-01-13T10:52:35Z")

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yes you are under windows so use load “MUMPS\_seq” or use mpi version …

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 13, 2022, 11:02am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/7 "2022-01-13T11:02:25Z")

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Thank you, professor.

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [January 15, 2022, 3:02am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/8 "2022-01-15T03:02:33Z")

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Hi, professor？why？  
(nan,nan) != (nan,nan) diff (nan,nan) =\> Sorry error in Optimization add: (p) int2d(Th,optimize=0)(…)  
remark if you add (… , optimize=2) then you remove this check (be careful);  
current line = 57  
Exec error : In Optimized version  
– number :1  
Exec error : In Optimized version  
– number :1

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<div class="post-metadata">

**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [January 25, 2022, 3:54pm UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/9 "2022-01-25T15:54:47Z")

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If you get nan (not a number) you system is not invertible so the problem of optimisation is other.

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<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [February 15, 2022, 9:14am UTC](https://community.freefem.org/t/some-problems-occurred-in-the-solution/1429/10 "2022-02-15T09:14:09Z")

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Thank you, professor. I found out，the parameter w = [0,1], but when parameter W \> 0.1 during programming, the matrix is irreversible. Why? There have been articles about this equation in w = [0,1], which has a very good well posedness.

 ![屏幕截图 2022-02-15 105354](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/1X/9bba0518f053427025b97634408abc9034cfaf7a.png)