faq.markdown

@@ -68,3 +68,47 @@ Then activate the following `GFORTRAN44_PATCHING` CMake flag:
 cmake . -DGFORTRAN44_PATCHING=True
 make
 ```
+
+##### An error arise when building the `matlib` on Mac OS Yosemite ####
+
+* if the error is something like:
+
+```shell
+/usr/include/dispatch/object.h:143:15: error: expected ')' before '^' token
+/usr/include/dispatch/object.h:362:3: error: 'dispatch_block_t' has not been declared
+   dispatch_block_t notification_block);
+   ^
+make[5]: *** [CMakeFiles/matlib.dir/src/math/eigmat.cpp.o] Error 1
+make[4]: *** [CMakeFiles/matlib.dir/all] Error 2
+make[3]: *** [all] Error 2
+make[2]: *** [src/contribs/matlib-prefix/src/matlib-stamp/matlib-build] Error 2
+make[1]: *** [src/contribs/CMakeFiles/matlib.dir/all] Error 2
+make: *** [all] Error 2
+```
+
+Then you can:
+
+* shut down the MatLib if you do not need it:
+
+```shell
+cmake . -DMATLIB_VERSION=none
+make
+```
+
+* or modifiy the file *src/contribs/MatLib4-LMGC-2015-1/src/math/lapack.h* so that it looks like this:
+
+```
+ #ifndef ZORGLIB_MATH_LAPACK_H
+ #define ZORGLIB_MATH_LAPACK_H
+ 
+ #ifndef __has_extension
+ #define __has_extension(x) 0
+ #endif
+
+ #define vImage_Utilities_h
+ #define vImage_CVUtilities_h
+ 
+ // config
+ #include <matlib_macros.h>
+```
+Then run `make` again.
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