Problem with compiling Intel's MKL CBLAS example file on macOS Catalina - c++

Question

I want to solve a problem in C++ which involves finding solutions to a system of equations. I saw that Intel's MKL package provides the necessary tools for that. I have downloaded the entire library and I've installed it.
First, I wanted to see if everything works, so compiling a simple example provided by intel (see the C source file here) was the first thing I've tried. It is a program that multiplies two matrices with the help of cblas_dgem function. However, I get a lot of warnings
and an error:
basavyr#Roberts-MacBook-Pro Desktop % g++ mkl-lab-solution.c
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
In file included from mkl-lab-solution.c:30:
In file included from /usr/local/include/stdio.h:64:
/usr/local/include/_stdio.h:93:16: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
unsigned char *_base;
^
/usr/local/include/_stdio.h:93:16: note: insert '_Nullable' if the pointer may be null
unsigned char *_base;
^
_Nullable
/usr/local/include/_stdio.h:93:16: note: insert '_Nonnull' if the pointer should never be null
unsigned char *_base;
^
_Nonnull
/usr/local/include/_stdio.h:138:32: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable _read) (void *, char *, int);
^
/usr/local/include/_stdio.h:138:32: note: insert '_Nullable' if the pointer may be null
int (* _Nullable _read) (void *, char *, int);
^
_Nullable
/usr/local/include/_stdio.h:138:32: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable _read) (void *, char *, int);
^
_Nonnull
/usr/local/include/_stdio.h:138:40: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable _read) (void *, char *, int);
^
/usr/local/include/_stdio.h:138:40: note: insert '_Nullable' if the pointer may be null
int (* _Nullable _read) (void *, char *, int);
^
_Nullable
/usr/local/include/_stdio.h:138:40: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable _read) (void *, char *, int);
^
_Nonnull
/usr/local/include/_stdio.h:139:35: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
fpos_t (* _Nullable _seek) (void *, fpos_t, int);
^
/usr/local/include/_stdio.h:139:35: note: insert '_Nullable' if the pointer may be null
fpos_t (* _Nullable _seek) (void *, fpos_t, int);
^
_Nullable
/usr/local/include/_stdio.h:139:35: note: insert '_Nonnull' if the pointer should never be null
fpos_t (* _Nullable _seek) (void *, fpos_t, int);
^
_Nonnull
/usr/local/include/_stdio.h:140:32: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable _write)(void *, const char *, int);
^
/usr/local/include/_stdio.h:140:32: note: insert '_Nullable' if the pointer may be null
int (* _Nullable _write)(void *, const char *, int);
^
_Nullable
/usr/local/include/_stdio.h:140:32: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable _write)(void *, const char *, int);
^
_Nonnull
/usr/local/include/_stdio.h:140:46: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable _write)(void *, const char *, int);
^
/usr/local/include/_stdio.h:140:46: note: insert '_Nullable' if the pointer may be null
int (* _Nullable _write)(void *, const char *, int);
^
_Nullable
/usr/local/include/_stdio.h:140:46: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable _write)(void *, const char *, int);
^
_Nonnull
/usr/local/include/_stdio.h:144:18: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
struct __sFILEX *_extra; /* additions to FILE to not break ABI */
^
/usr/local/include/_stdio.h:144:18: note: insert '_Nullable' if the pointer may be null
struct __sFILEX *_extra; /* additions to FILE to not break ABI */
^
_Nullable
/usr/local/include/_stdio.h:144:18: note: insert '_Nonnull' if the pointer should never be null
struct __sFILEX *_extra; /* additions to FILE to not break ABI */
^
_Nonnull
In file included from mkl-lab-solution.c:30:
/usr/local/include/stdio.h:67:13: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
extern FILE *__stdinp;
^
/usr/local/include/stdio.h:67:13: note: insert '_Nullable' if the pointer may be null
extern FILE *__stdinp;
^
_Nullable
/usr/local/include/stdio.h:67:13: note: insert '_Nonnull' if the pointer should never be null
extern FILE *__stdinp;
^
_Nonnull
/usr/local/include/stdio.h:386:41: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable)(void *, const char *, int),
^
/usr/local/include/stdio.h:386:41: note: insert '_Nullable' if the pointer may be null
int (* _Nullable)(void *, const char *, int),
^
_Nullable
/usr/local/include/stdio.h:386:41: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable)(void *, const char *, int),
^
_Nonnull
/usr/local/include/stdio.h:386:55: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable)(void *, const char *, int),
^
/usr/local/include/stdio.h:386:55: note: insert '_Nullable' if the pointer may be null
int (* _Nullable)(void *, const char *, int),
^
_Nullable
/usr/local/include/stdio.h:386:55: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable)(void *, const char *, int),
^
_Nonnull
/usr/local/include/stdio.h:387:44: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
fpos_t (* _Nullable)(void *, fpos_t, int),
^
/usr/local/include/stdio.h:387:44: note: insert '_Nullable' if the pointer may be null
fpos_t (* _Nullable)(void *, fpos_t, int),
^
_Nullable
/usr/local/include/stdio.h:387:44: note: insert '_Nonnull' if the pointer should never be null
fpos_t (* _Nullable)(void *, fpos_t, int),
^
_Nonnull
/usr/local/include/stdio.h:388:41: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
int (* _Nullable)(void *));
^
/usr/local/include/stdio.h:388:41: note: insert '_Nullable' if the pointer may be null
int (* _Nullable)(void *));
^
_Nullable
/usr/local/include/stdio.h:388:41: note: insert '_Nonnull' if the pointer should never be null
int (* _Nullable)(void *));
^
_Nonnull
/usr/local/include/stdio.h:384:6: warning: pointer is missing a nullability type specifier
(_Nonnull, _Nullable, or _Null_unspecified) [-Wnullability-completeness]
FILE *funopen(const void *,
^
/usr/local/include/stdio.h:384:6: note: insert '_Nullable' if the pointer may be null
FILE *funopen(const void *,
^
_Nullable
/usr/local/include/stdio.h:384:6: note: insert '_Nonnull' if the pointer should never be null
FILE *funopen(const void *,
^
_Nonnull
mkl-lab-solution.c:85:15: warning: conversion from string literal to 'char *' is deprecated
[-Wc++11-compat-deprecated-writable-strings]
print_arr(N,"a", a);
^
mkl-lab-solution.c:86:15: warning: conversion from string literal to 'char *' is deprecated
[-Wc++11-compat-deprecated-writable-strings]
print_arr(N,"b", b);
^
mkl-lab-solution.c:87:15: warning: conversion from string literal to 'char *' is deprecated
[-Wc++11-compat-deprecated-writable-strings]
print_arr(N,"c", c);
^
16 warnings generated.
Undefined symbols for architecture x86_64:
"_cblas_dgemm", referenced from:
Dgemm_multiply(double*, double*, double*, int) in mkl-lab-solution-96315a.o
ld: symbol(s) not found for architecture x86_64
**clang: error:** linker command failed with exit code 1 (use -v to see invocation)
basavyr#Roberts-MacBook-Pro Desktop %
Compilation was done with the following command: g++ -m64 -I${MKLROOT}/include mkl-lab-solution.c
I am running macOS Catalina (10.15.3). I have no issues with my C++ compiler (I ran everything so far without issues)
Any ideas why is this happening and how can I solve the problem?

Answer 1

You need to link with mkl's libraries. Please refer to the mkl linker adviser to see the list of mkl's libs you need to link. here is the list to this adviser: https://software.intel.com/en-us/articles/intel-mkl-link-line-advisor.