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mex fortran code containing intrinsic function using Intel fortran compiler

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Duy Nguyen
Duy Nguyen on 24 Sep 2019
Edited: Duy Nguyen on 25 Sep 2019
Hi,
I'm trying to mex a fortran code using the Intel Parallel studio XE 2019 with microsoft visual studio 2015 compiler. My fortran code calls intrinsic functions cosd, sind, and atand. However, the linker keeps complaining that these are unresolved external symbols. Are there libraries that I need to link in during the mex that will define these intrinsic functions? Thanks.
Error using mex
Creating library rcssig.lib and object rcssig.exp
read_reftab.obj : error LNK2019: unresolved external symbol COSD referenced in
function READ_REFTAB
body_to_range.obj : error LNK2001: unresolved external symbol COSD

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Accepted Answer

A King
A King on 25 Sep 2019
Edited: A King on 25 Sep 2019
cosd, sind, atand, are NOT part of the Fortran standard, they are GNU extensions to the Fortran language and not understandable by Intel. These GNU functions take the angle in degree instead of radians (which is the deafult Fortran standard for sin, cos, atan). If you want to compile the files by Intel, multiply the arguments of all instances of cosd, sind by pi/180 = 0.01745329251, which converts the angles in degrees to radians, then replace all of the instances of cosd, sind, with cos, sin respectively, which are part of the Fortran standard and that should resolve the error.
As for atand, this function returns angle in degrees, so you will have to replace atand() with 57.2957795131 * atan()
where 57.2957795131 = 180/pi

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James Tursa
James Tursa on 25 Sep 2019
From the Intel Fortran website:
Also note that OP specifically stated his compiler understands cosd( ) just fine in a standalone compile, just not in a mex compile.
Duy Nguyen
Duy Nguyen on 25 Sep 2019
Perfect! Thank you so much.
Wished I had read that earlier from the Fortran website, would have saved me tons of time trying to figure out why cosd compiles in standalone mode but not in mex :) Thank you!!!!!

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More Answers (1)

James Tursa
James Tursa on 24 Sep 2019
Edited: James Tursa on 24 Sep 2019
Can you post the offending code? Maybe you are calling it with a non-real argument and the compiler is complaining that it can't find a specific function for your specific argument type.
How are you doing the compiling and linking? With the mex command, or building from within the Visual Studio environment?

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Duy Nguyen
Duy Nguyen on 24 Sep 2019
Hi,
This is a sample call that I make: pitch(1,1)=COSD(pitch_angle), where pitch_angle is a real number.
The code compiles and runs just fine within the Visual Studio 2015 and 2017 environment. But when I try to mex it within Matlab, I get the undefined external error. I looked at the build log file generated by the Visual Studio 2015 compiler and see no library that I need to link in, so I can't figure out what the Mex is looking for to resolve cosd.
Thanks.

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