更新11/23/2019：最初的问题是为什么我不能让f2py用于简单的fortran包装器。我的“答案”（如下）是改用ctypes。
原始帖子：最近三天，我一直在尝试使用f2py将fortran与python接口。我正在使用cygwin和mingw在Windows上工作。这篇文章是关于使用cygwin的，但是我担心两者之间的冲突。这是源文件multxy.f90：
subroutine multxy(x,y,z)
integer, parameter :: flt = selected_real_kind(15)
real(flt), intent(in) :: x,y
real(flt), intent(out) :: z
write(*,'(a,3g12.5)')'multxy'
write(*,'(a,3g12.5)')'multxy',x,y,x*y
z = x*y
end subroutine multxy
如果我像看过的所有示例一样运行f2py：f2py -m multxyC -c multxy.f90产生链接错误。在数以吨计的产量中，我抱怨strtoflt128。这是gnu gcc quad数学库中的函数。我的flt类相当于C中的double。代码中没有四位数学，那么为什么要使用它呢？我试图创建一个扩展文件来查看它是否可以告诉我任何内容，但它仍尝试链接，因此未生成（或保存）任何代码。至此，我使用strtofl128构建了一个小型c程序。如果我包含Quadmath库，它将编译并链接：gcc main.c -lquadmath它无法正常运行，但是稍后我会对此进行研究。我相信实际的四方库文件是…./cwin/lib/gcc/x86_64-pc-cygwin/8.3.0/libquadmath.a。运行f2py的输出显示此目录，因此您会认为它将链接库。我尝试使用-l选项的各种变体运行f2py。通常它会抱怨找不到库。我可以使用一种变体，但是链接仍然失败。我还使用了整数函数：
integer function intfunc(n)
integer, intent(in) :: n
intfunc = n*n
end function intfunc
我已经能够创建一个dll并从python调用它，而无需使用f2py。它似乎通过f2py运行就好了。它创建一个文件intfunc.cp37-win_amd64.pyd和一个目录，该目录包含一个具有很大名称的.dll。我还无法从python调用它，但我会继续努力。
问题：
f2py被吹捧为易于使用。也许是这样，但是只有在您使其正常工作之后。例如，我从事不同语言的交流已有25年了。 c / c ++，fortran，excel / vba，matlab / octave，几乎没有这么多困难。这似乎是一个程序，很多事情都被隐藏了起来，很难解决。
一个问题是，运行f2py的输出与核心转储一样容易读取。运行时的输出是：
running build
running config_cc
unifing config_cc, config, build_clib, build_ext, build commands --compiler options
running config_fc
unifing config_fc, config, build_clib, build_ext, build commands --fcompiler options
running build_src
build_src
building extension "multxyC" sources
f2py options: []
f2py:> C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\multxyCmodule.c
creating C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7
Reading fortran codes...
Reading file 'multxy.f90' (format:free)
Post-processing...
Block: multxyC
Block: multxy
Post-processing (stage 2)...
Building modules...
Building module "multxyC"...
Constructing wrapper function "multxy"...
z = multxy(x,y)
Wrote C/API module "multxyC" to file "C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\multxyCmodule.c"
adding 'C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\fortranobject.c' to sources.
adding 'C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7' to include_dirs.
copying c:\program files\python37\lib\site-packages\numpy\f2py\src\fortranobject.c -> C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7
copying c:\program files\python37\lib\site-packages\numpy\f2py\src\fortranobject.h -> C:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7
build_src: building npy-pkg config files
running build_ext
No module named 'numpy.distutils._msvccompiler' in numpy.distutils; trying from distutils
customize MSVCCompiler
customize MSVCCompiler using build_ext
get_default_fcompiler: matching types: '['gnu', 'intelv', 'absoft', 'compaqv', 'intelev', 'gnu95', 'g95', 'intelvem', 'intelem', 'flang']'
customize GnuFCompiler
Could not locate executable g77
Could not locate executable f77
customize IntelVisualFCompiler
Could not locate executable ifort
Could not locate executable ifl
customize AbsoftFCompiler
Could not locate executable f90
customize CompaqVisualFCompiler
Found executable C:\cwin\bin\DF.exe
customize IntelItaniumVisualFCompiler
Could not locate executable efl
customize Gnu95FCompiler
Found executable C:\cwin\bin\gfortran.exe
Using built-in specs.
COLLECT_GCC=/usr/bin/gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/8.3.0/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with: /cygdrive/i/szsz/tmpp/gcc/gcc-8.3.0-1.x86_64/src/gcc-8.3.0/configure --srcdir=/cygdrive/i/szsz/tmpp/gcc/gcc-8.3.0-1.x86_64/src/gcc-8.3.0 --prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc --docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C --build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin --without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib --enable-shared --enable-shared-libgcc --enable-static --enable-version-specific-runtime-libs --enable-bootstrap --enable-__cxa_atexit --with-dwarf2 --with-tune=generic --enable-languages=ada,c,c++,fortran,lto,objc,obj-c++ --enable-graphite --enable-threads=posix --enable-libatomic --enable-libgomp --enable-libitm --enable-libquadmath --enable-libquadmath-support --disable-libssp --enable-libada --disable-symvers --with-gnu-ld --with-gnu-as --with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix --without-libintl-prefix --with-system-zlib --enable-linker-build-id --with-default-libstdcxx-abi=gcc4-compatible --enable-libstdcxx-filesystem-ts
Thread model: posix
gcc version 8.3.0 (GCC)
customize Gnu95FCompiler
Using built-in specs.
COLLECT_GCC=/usr/bin/gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/8.3.0/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with: /cygdrive/i/szsz/tmpp/gcc/gcc-8.3.0-1.x86_64/src/gcc-8.3.0/configure --srcdir=/cygdrive/i/szsz/tmpp/gcc/gcc-8.3.0-1.x86_64/src/gcc-8.3.0 --prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc --docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C --build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin --without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib --enable-shared --enable-shared-libgcc --enable-static --enable-version-specific-runtime-libs --enable-bootstrap --enable-__cxa_atexit --with-dwarf2 --with-tune=generic --enable-languages=ada,c,c++,fortran,lto,objc,obj-c++ --enable-graphite --enable-threads=posix --enable-libatomic --enable-libgomp --enable-libitm --enable-libquadmath --enable-libquadmath-support --disable-libssp --enable-libada --disable-symvers --with-gnu-ld --with-gnu-as --with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix --without-libintl-prefix --with-system-zlib --enable-linker-build-id --with-default-libstdcxx-abi=gcc4-compatible --enable-libstdcxx-filesystem-ts
Thread model: posix
gcc version 8.3.0 (GCC)
customize Gnu95FCompiler using build_ext
building 'multxyC' extension
compiling C sources
creating C:\cwin\tmp\tmprix0z7i7\Release\cwin
creating C:\cwin\tmp\tmprix0z7i7\Release\cwin\tmp
creating C:\cwin\tmp\tmprix0z7i7\Release\cwin\tmp\tmprix0z7i7
creating C:\cwin\tmp\tmprix0z7i7\Release\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MT -IC:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7 -Ic:\program files\python37\lib\site-packages\numpy\core\include -Ic:\program files\python37\include -Ic:\program files\python37\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\ATLMFC\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt /TcC:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\multxyCmodule.c /FoC:\cwin\tmp\tmprix0z7i7\Release\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\multxyCmodule.obj
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MT -IC:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7 -Ic:\program files\python37\lib\site-packages\numpy\core\include -Ic:\program files\python37\include -Ic:\program files\python37\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\ATLMFC\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt /TcC:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\fortranobject.c /FoC:\cwin\tmp\tmprix0z7i7\Release\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7\fortranobject.obj
compiling Fortran sources
Fortran f77 compiler: C:\cwin\bin\gfortran.exe -Wall -g -ffixed-form -fno-second-underscore -O3 -funroll-loops
Fortran f90 compiler: C:\cwin\bin\gfortran.exe -Wall -g -fno-second-underscore -O3 -funroll-loops
Fortran fix compiler: C:\cwin\bin\gfortran.exe -Wall -g -ffixed-form -fno-second-underscore -Wall -g -fno-second-underscore -O3 -funroll-loops
compile options: '-IC:\cwin\tmp\tmprix0z7i7\src.win-amd64-3.7 -Ic:\program files\python37\lib\site-packages\numpy\core\include -Ic:\program files\python37\include -Ic:\program files\python37\include -c'
gfortran.exe:f90: multxy.f90
C:\cwin\bin\gfortran.exe -Wall -g -Wall -g -shared ..\..\..\..\cwin\tmp\tmprix0z7i7\Release\multxy.o -L/usr/lib/gcc/x86_64-pc-cygwin/8.3.0 -Lc:\program files\python37\libs -Lc:\program files\python37\PCbuild\amd64 -o C:\cwin\tmp\tmprix0z7i7\Release\.libs\libmultxy.J7YCD6VUIR3DWPQ3PSLGVWZTCQ2KMJO6.gfortran-win_amd64.dll -Wl,--allow-multiple-definition -Wl,--output-def,C:\cwin\tmp\tmprix0z7i7\Release\libmultxy.J7YCD6VUIR3DWPQ3PSLGVWZTCQ2KMJO6.gfortran-win_amd64.def -Wl,--export-all-symbols -Wl,--enable-auto-import -static -mlong-double-64
/usr/lib/gcc/x86_64-pc-cygwin/8.3.0/../../../../x86_64-pc-cygwin/bin/ld: /usr/lib/gcc/x86_64-pc-cygwin/8.3.0/libgfortran.a(read.o): in function `_gfortrani_convert_real':
/usr/src/debug/gcc-8.3.0-1/libgfortran/io/read.c:173:(.text$_gfortrani_convert_real+0x85): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `strtoflt128'
/usr/lib/gcc/x86_64-pc-cygwin/8.3.0/../../../../x86_64-pc-cygwin/bin/ld: /usr/lib/gcc/x86_64-pc-cygwin/8.3.0/libgfortran.a(read.o): in function `_gfortrani_convert_infnan':
/usr/src/debug/gcc-8.3.0-1/libgfortran/io/read.c:249:(.text$_gfortrani_convert_infnan+0x5c): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `strtoflt128'
collect2: error: ld returned 1 exit status
error: Command "C:\cwin\bin\gfortran.exe -Wall -g -Wall -g -shared ..\..\..\..\cwin\tmp\tmprix0z7i7\Release\multxy.o -L/usr/lib/gcc/x86_64-pc-cygwin/8.3.0 -Lc:\program files\python37\libs -Lc:\program files\python37\PCbuild\amd64 -o C:\cwin\tmp\tmprix0z7i7\Release\.libs\libmultxy.J7YCD6VUIR3DWPQ3PSLGVWZTCQ2KMJO6.gfortran-win_amd64.dll -Wl,--allow-multiple-definition -Wl,--output-def,C:\cwin\tmp\tmprix0z7i7\Release\libmultxy.J7YCD6VUIR3DWPQ3PSLGVWZTCQ2KMJO6.gfortran-win_amd64.def -Wl,--export-all-symbols -Wl,--enable-auto-import -static -mlong-double-64" failed with exit status 1
我没有完全弄清f2py的问题，所以请不要为这个非答案而烦恼。我想要做的只是在一些fortran周围放一个简单的包装。我虽然解决了这个问题，所以这篇文章是我的答案。我正在发布它，希望它可以帮助遇到类似问题的其他人。
发布后，我决定我需要降低到较低的级别以了解发生了什么。由于f2py是基于C-api构建的，因此我决定直接使用它。 C-fortran互操作性已得到很好的定义。我有一些简单的代码可以工作，但是当我开始查看传递数组并阅读有关引用计数的信息时，我被吓到了。因此，我认为C-api的水平太低，无法满足我的需求。 Cython似乎是针对编写可编译的类似Python的代码。我最终决定使用ctypes，因为我真正需要的只是转换内部python类型，然后调用（它认为是）c代码。周围有一些示例，但似乎没有一个完全合适，因此我将发布一些测试代码，以希望对其他人有帮助。该示例显示了通过函数和子例程来回传递int，double和array的情况。如果将.so替换为.dll，则在Windows中也可以使用相同的代码。此信息很有帮助-How to dereference a memory location from python ctypes?
fortran是：
Integer Function intfunc(n)
integer, intent(in) :: n
intfunc = n*n
end Function intfunc
! ---------------------------------------------------------------------------------------
subroutine Asub(acf,af)
include 'defs.fi' ! integer, parameter :: float = selected_real_kind(12)
Real(float), intent(in) :: acf
Real(float), intent(out) :: af
if(acf < 0.49)then
af = 0.37464 + acf*(1.54226 - 0.26992*acf)
else
af = 0.379642 + acf*(1.48503 + acf*(-0.164423 + 0.016666*acf))
endif
end subroutine Asub
! ---------------------------------------------------------------------------------------
Function Afactor(acf) result(af)
include 'defs.fi'
Real(float), intent(in) :: acf
Real(float) :: af
if(acf < 0.49)then
af = 0.37464 + acf*(1.54226 - 0.26992*acf)
else
af = 0.379642 + acf*(1.48503 + acf*(-0.164423 + 0.016666*acf))
endif
End Function Afactor
! ---------------------------------------------------------------------------------------
Function MultXY(x,y) result(z)
include 'defs.fi'
Real(float), intent(in) :: x,y
Real(float)::z
z = x*y
End Function MultXY
! ---------------------------------------------------------------------------------------
subroutine arrays(n,m,a)
include 'defs.fi'
integer, intent(in) :: n,m
real(float), intent(out) :: a(n,m)
integer :: i,j
do j=1,m
do i=1,n
a(i,j) = real(100*i+j,float)
enddo
enddo
end subroutine arrays
该代码通过以下方式编译到共享库中：
gfortran -shared -o code.so code.f90 -fPIC -Xlinker -Map=code.map
它可以与以下python代码一起运行。可以将这段代码中的许多步骤组合在一起，但是我认为将它们分解更能说明问题。我不完全了解函数原型（argtypes和restypes）。它们似乎允许一些快捷方式，例如Python执行适当的强制转换。有人可以详细说明吗？
import ctypes as ct
import numpy as np
from numpy.ctypeslib import ndpointer
flib = ct.CDLL('code.so')
flib.asub_.argtypes = [ct.POINTER(ct.c_double),ct.POINTER(ct.c_double)]
flib.afactor_.argtypes = [ct.POINTER(ct.c_double)]
flib.afactor_.restype = ct.c_double
flib.multxy_.argtypes = [ct.POINTER(ct.c_double),ct.POINTER(ct.c_double)]
flib.multxy_.restype = ct.c_double
flib.arrays_.argtypes = [ct.POINTER(ct.c_int),ct.POINTER(ct.c_int),ndpointer(ct.c_double)]
def main():
nval = 4
nptr = ct.pointer(ct.c_int(nval))
# integer function intfunc(n)
nx = flib.intfunc_(nptr)
print('intfunc(',nval,') =',nx)
x = 0.35
xc = ct.c_double(x)
yc = ct.c_double(0.50)
zc = ct.c_double(0.0)
# subroutine Asub(acf,af)
flib.asub_(ct.byref(xc),ct.byref(zc))
z = zc.value
x = xc.value
y = yc.value
print(' x,z =',x,z)
# Function Afactor(acf) result(af)
z = flib.afactor_(ct.byref(xc))
print(' x,z =',x,z)
# Function MultXY(x,y) result(z)
z = flib.multxy_(ct.byref(xc),ct.byref(yc))
print('multxy(',x,y,') =',z)
n = 3
m = 4
nc = ct.c_int(n)
mc = ct.c_int(m)
a = np.empty((m,n),dtype=np.double) # m,n not n,m
# subroutine arrays(n,m,a)
flib.arrays_(ct.byref(nc),ct.byref(mc),a)
for i in range(n): # note reversal of indices
for j in range(m):
print('i,j,a(j,i) =',i+1,j+1,a[j,i])
main()
输出为：
intfunc( 4 ) = 16
x,z = 0.35 0.8813658067584037
x,z = 0.35 0.8813658067584037
multxy( 0.35 0.5 ) = 0.175
i,j,a(j,i) = 1 1 101.0
i,j,a(j,i) = 1 2 102.0
i,j,a(j,i) = 1 3 103.0
i,j,a(j,i) = 1 4 104.0
i,j,a(j,i) = 2 1 201.0
i,j,a(j,i) = 2 2 202.0
i,j,a(j,i) = 2 3 203.0
i,j,a(j,i) = 2 4 204.0
i,j,a(j,i) = 3 1 301.0
i,j,a(j,i) = 3 2 302.0
i,j,a(j,i) = 3 3 303.0
i,j,a(j,i) = 3 4 304.0