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10496 :: ggplotnim and lapack

• rajmac (orginal) [2023-09-19T17:47:26+02:00] view original

  As a newcomer to nim I have been impressed in using it and getting to grips with its syntax. Recently I wanted to try using ggplotnim to produce some graphs. Initially I installed the package on my windows 11 machine, including the cairo.dll as mentioned in the documentation, but when using it I got the message 'could not find lapack.dll'. The plots were all simple line graphs. To check I wasn't doing anything silly I checked my code by installing nim on my linux machine and everything worked as it should and the plots were fine. I found the lapack.dll on the microsoft site and installed it in the Windows system 32 folder but this didn't help. I have been unable to find a work around for the Lapack problem and wondered if anyone could help me. I am using Nim Compiler Version 2.0.0 [Windows: amd64] and nimble v0.14.2. The ggplotnim was installed with the reccommended nimble install ggplotnim. Apologies if I'm being stupid. Thanks in advance for any insights?.

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• didlybom (orginal) [2023-09-19T18:05:47+02:00] view original

  I think that Lapack was recently added as a dependency for some new feature. I believe that you can pass the -d:nolapack flag when compiling. Hopefully that will fix your issue. If it is not in the readme it should be added there :)

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• Vindaar (orginal) [2023-09-20T00:25:16+02:00] view original

  Sorry for the inconvenience!

  Ass @didlybom correctly points out, the LAPACK dependency came about somewhat "recently" in version v0.4.4 and the -d:nolapack compilation flag was then added in v0.5.0 for the reason you encountered. Installing LAPACK on Windows can be a bit of a pain. In the Github Actions CI we use msys2 for Windows to install LAPACK:

  https://github.com/Vindaar/ggplotnim/blob/master/.github/workflows/ci.yml#L71

  I should have put that into the README under the Windows notes!

  Now why do we end up with the LAPACK dependency in the first place? geom_smooth requires it. geom_smooth computes a Savitzky-Golay filter to smooth the input data using a polynomial fit, which is done using a linear least squares routine from arraymancer, which depends on LAPACK. I've been meaning to (at least optionally) provide an alternative implementation that uses pure Nim code for this (@c-blake already has code in his https://github.com/c-blake/fitl that would be useful).

  And the reason this also happens when simply compiling a basic line plot is that the different geom_* are mapped to a variant object. That means which Geom is used is effectively decided at runtime, so there is no way to know that the LAPACK dependency might not be needed.

  If you have further questions, feel free to just ping me on matrix/discord!

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