Undefined function or variable 'lgamma'.

2021 1 25
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更新时间：2021 2 8
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Hello experts,
as the title says I have a problem with this undefined 'lgamma'.
I'm trying to run an ANCOVA using the function aoctool() but it stops and throws me that error.
Below I post the entire message:
Undefined function or variable 'lgamma'.
Error in betapdf (line 60)
+ lgamma (a + b) - lgamma (a) - lgamma (b));
Error in betainv (line 87)
h = (betacdf (y_old, a, b) - x) ./ betapdf (y_old, a, b);
Error in finv (line 58)
inv(k) = ((1 ./ betainv (1 - x(k), n/2, m/2) - 1) * n / m);
Error in aoctool>getyvalues (line 777)
crit = sqrt(df1 * finv(1-alpha/bonf, df1, df2));
Error in aoctool (line 335)
[newy, ~, ycov] = getyvalues(allx, allgrps, model, stats, ud);
I'm working on MATLAB R2018b.
Is this related with a MATLAB issue or (most likely) it's just me erroneously defining the ANCOVA variables?
Thank you for your help!
Marco

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Adam Danz
Adam Danz 2021-1-26
I'm aware of a gamma function but not a function named lgamma.
It is a variable name? Did the function come from some other source outside of Matlab?
Star Strider
Star Strider 2021-1-26
You need to Contact Support .
I opened betapdf.m in the MATLAB editor, and the last line of the function is 58. That line contains a betaln call, and there are no gamma function calls of any kind in the entire function. (I am using R2020b.)
NMarco
NMarco 2021-1-26
@Adam Danz , @Star Strider thank you for your feedback.
The lgamma is from a internal MATLAB code, that's why I'm concerned about this error.
I will contact the support, I guess..
Thanks anyway!

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 采纳的回答

Walter Roberson
Walter Roberson 2021-1-26

1 个投票

I see relevant discussion at https://github.com/wichmann-lab/psignifit/issues/4 . The implications there are that you are picking up a third-party toolbox version of finv that is invoking a third-party betainv that is invoking a third-party betapdf that is asking for lgamma that has not been part of MATLAB for a number of years.
The fix would be to move those that third-party finv (and related) out of your MATLAB path.
By the way, the Mathworks long gamma function is gammaln() these days, and is part of basic MATLAB.

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NMarco
NMarco 2021-1-26
编辑：NMarco 2021-1-26
Thank you for your reply.
I explored where the finv and betainv and betapdf were located and all of them were part of SPM12 software (for brain imaging analysis).
>> which finv
C:\Users\me\Desktop\MATLAB\R2018b_windows\spm12\spm12\external\fieldtrip\external\stats\finv.m
>> which betainv
C:\Users\me\Desktop\MATLAB\R2018b_windows\spm12\spm12\external\fieldtrip\external\stats\betainv.m
>> which betapdf
C:\Users\me\Desktop\MATLAB\R2018b_windows\spm12\spm12\external\fieldtrip\external\stats\betapdf.m
Because right now I don't need to use SPM software, I removed that specific folder from the path
rmpath C:\Users\me\Desktop\MATLAB\R2018b_windows\spm12\spm12\external\fieldtrip\external\stats
And now everything works fine.
I really appreciate your help!
Qiuxia Wu
Qiuxia Wu 2021-2-7
I got the same issue when I use pTFCE within Matlab2020b. The problem is, I need to use SPM12, is there anything I could do to fix it?
NMarco
NMarco 2021-2-8
Cannot you use one before or after the other? Like, use SPM and than make calculations using pTFE upon removing that folder from the path.
Walter Roberson
Walter Roberson 2021-2-8
https://miplab.epfl.ch/BrainHack/Practice/Utilities/spm12/external/fieldtrip/external/stats/ shows that lgamma.m is defined in the external/fieldtrip/external/stats directory that is installed with SPM12.

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