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I'm using python3.6 theano, with mingw-w64-x86-64 installed, my os is Win10_64, cuda installed, and seems everything is ok

the theano.test() is ok, saying my gpu is working,

but it just keeps tell me that "error: '::hypot' has not been declared"

 C:/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/cmath:1157:11: error: '::hypot' has 
 not been declared\r.    using ::hypot;\r.            ^~~~~\r. ",

Any help would be appreciated!

YJHMITWEB
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4 Answers4

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I had this error with building an python file using mingw32 . I opened the file that it says (C:/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/cmath:1157:11)
and changed that line to 

using ::_hypot;

or adding this line just before that : 

#define hypot _hypot

and after that the problem was solved !! I know it's not a basic solution but it is the one that I could find !!

it_nazanin
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  • Oh, yes! It works for ...\mingw-w64\mingw64\lib\gcc\x86_64-w64-mingw32\8.1.0\include\c++\cmath : 1121 – sherdim Apr 06 '19 at 08:23
  • https://github.com/Theano/Theano/issues/4926 also advises to add THEANO_FLAGS='gcc.cxxflags="-D_hypot=hypot"' to the environment variables. – sherdim Apr 06 '19 at 08:46
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    I had to keep the original mingw cmath header (otherwise libpng would not build) and I commented out the #define hypot _hypot in pyconfig.h (line 241). Worked for me. – Hwy2Hell May 26 '19 at 09:43
  • I'd strongly recommend against editing system header files as it will just munt things up for any other times you use the compiler for other projects, and could lead to a "butterfly effect" of weird consequences . – M.M Mar 26 '20 at 23:18
2

(This answer was posted in comments originally)

I had to keep the original mingw cmath header (otherwise libpng would not build) and I commented out the #define hypot _hypot in pyconfig.h (line 241).

M.M
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1

What worked for me was to use the combination of the answers above:

#ifdef _WIN64
#define _hypot hypot
#include <cmath>
#endif
#include <pybind11.h>
Adam Husár
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0

My guess from your incomplete information is that you aren't compiling in C++11 mode so you aren't picking up ::hypot from C99.

Mark B
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