盡管鏈接到數學庫，但未定義對`sqrt`的引用

Question

我正在嘗試從英特爾MKL庫（ /opt/intel/mkl/examples/versionqueryc/ ）編譯示例程序。 我將源代碼（C文件）復制到一個新目錄。 然后我去嘗試用CMake構建這個例子。

在調試過程中，我在嘗試使用以下命令時遇到困難（現在與cmake隔離）。

它沒有找到數學庫，但我在鏈接中包含了-lm 。 那么發生了什么？

:~/devel/mkl/MKL Test/build$  /usr/bin/gcc -m64 CMakeFiles/mkltest.dir/main.c.o \
>     -o mkltest    -rdynamic -L/home/myuser/src/intel/mkl/lib/intel64 \
>     -lm  -lmkl_intel_lp64 -lmkl_sequential -lmkl_core  -lmkl_cdft_core \
>     -lmkl_scalapack_lp64 \
>     /home/myuser/src/intel/lib/intel64/libiomp5.so \
>     -Wl,-rpath,/home/myuser/src/intel/mkl/lib/intel64:/home/myuser/src/intel/lib/intel64 
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `logf'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `atan2'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `sin'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `fabs'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `exp'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `sqrtf'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `cos'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `sqrt'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_sequential.so: undefined reference to `log'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `pow'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `log10'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `ceil'
/home/myuser/src/intel/mkl/lib/intel64/libmkl_core.so: undefined reference to `expf'
collect2: ld returned 1 exit status

Answer 1

將-lm作為最后一個參數，鏈接時參數的順序很重要。