Why MEX cannot find library 'm' specified with the -l option?

I compiling some c files to make mex files in windows 10 64-bit operating system. but when I run it gives the following error:

Error using mex
MEX cannot find library 'm' specified with the -l option.
 MEX looks for a file with one of the names:
 m.lib
 libm.lib
 Please specify the path to this library with the -L option.

Error in make (line 17)

mex CC=g++ -lm get_full_speed.c

[Walter Roberson]

I see a hint that libm might be built in for MinGW

Also, http://www.mingw.org/wiki/specify_the_libraries_for_the_linker_to_use says you should use

mex CC=g++ get_full_speed.c -lm

in the sense that it says that -l libraries need to go after the objects that reference them.

[K M Ibrahim Khalilullah]

Thanks. still has this problem:

Error using mex MEX cannot find library 'm' specified with the -l option. MEX looks for a file with one of the names: m.lib libm.lib Please specify the path to this library with the -L option.

Error in make (line 17)

mex CC=g++ get_full_speed.c -lm

[Walter Roberson]

Try without the -lm at all

[K M Ibrahim Khalilullah]

Thanks, it is ok without using -lm.

[K M Ibrahim Khalilullah]

@Walter Roberson How can I accept your answer?

[Soham Patel]

mex -O -I/usr/include/opencv -lcxcore -lcv -lhighgui -c seeds2.cpp

mex -O mexSEEDS.cpp -I/usr/include/opencv -lcxcore -lcv -lhighgui seeds2.o

i am getting error in this file

MEX cannot find library 'cxcore' specified with the -l option.
MEX looks for a file with one of the names:
libcxcore.lib
cxcore.lib
Please specify the path to this library with the -L option.

can you help me to solved this error?

my opencv folder in c drive in download "C:\Users\Admin\Downloads\opencv"

can you help to write path of opencv?

[Walter Roberson]

mex -O -I/usr/include/opencv -LC:/Users/Admin/Downloads/opencv -lcxcore -lcv -lhighgui -c seeds2.cpp

I suspect you will also need to change the -I/usr/include/opencv to something else, but where will depend on where the opencv include files got installed. possibly

mex -O -IC:/Users/Admin/Downloads/opencv/include -LC:/Users/Admin/Downloads/opencv -lcxcore -lcv -lhighgui -c seeds2.cpp

Answer 1

[Walter Roberson]

I see a hint that libm might be built in for MinGW. Try without the -lm

[Zhibin Deng]

How to achieve this?

[Walter Roberson]

The original code was

mex CC=g++ -lm get_full_speed.c

instead you would use

mex CC=g++ get_full_speed.c

Answer 2

[timo]

I have a similar issue . Didnt help not to use -l

>> mex -v -L"c:\MATLAB\R2018a\extern\lib\win64\mingw64" -liphlpapi MACAddress_mex.c
Verbose mode is on.
... Looking for compiler 'MinGW64 Compiler (C)' ...
... Looking for environment variable 'MW_MINGW64_LOC' ...Yes ('C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset').
... Looking for file 'C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\bin\gcc.exe' ...Yes.
... Looking for folder 'C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset' ...Yes.
Found installed compiler 'MinGW64 Compiler (C)'.
Set PATH = C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\bin;C:\MATLAB\R2018a\extern\include\win64;C:\MATLAB\R2018a\extern\include;C:\MATLAB\R2018a\simulink\include;C:\MATLAB\R2018a\lib\win64;C:\ProgramData\Oracle\Java\javapath;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files\TortoiseSVN\bin;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files\dotnet\;C:\TDM-GCC-64\bin;C:\MATLAB\R2018a\bin;C:\Users\timo\AppData\Local\Microsoft\WindowsApps;c:\SysGCC\mingw64\bin;
Set INCLUDE = C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\include;;C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\include;;
Set LIB = C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\lib;;C:\ProgramData\MATLAB\SupportPackages\R2018a_1\3P.instrset\mingw_w64.instrset\lib;;
Set MW_TARGET_ARCH = win64;win64;
Set LIBPATH = C:\MATLAB\R2018a\extern\lib\win64;C:\MATLAB\R2018a\extern\lib\win64;
Error using mex
MEX cannot find library 'iphlpapi' specified with the -l option.
 MEX looks for a file with one of the names:
 libiphlpapi.lib
 iphlpapi.lib
 Please specify the path to this library with the -L option.

[Walter Roberson]

You should be using the order

mex -v -L"c:\MATLAB\R2018a\extern\lib\win64\mingw64" MACAddress_mex.c -liphlpapi

However, I am not sure where you would find a MinGW compatible iphlpapi.lib . I see that it is normally provided with VS SDK

What I do find is https://github.com/jonasstrandstedt/MinGW/tree/master/MinGW/lib

has iphlpapi.a . I am not sure if that implies that you would have that file in the directory that you -L'd . If so then

mex -v -L"c:\MATLAB\R2018a\extern\lib\win64\mingw64" MACAddress_mex.c iphlpapi.a