调用BLAS函数 [英] Calling BLAS functions

问题描述

这是一个简单的程序

PROGRAM MAIN
implicit none
integer, PARAMETER :: N=10
real*8 :: A(N)
real*8 :: x=0.1D0
integer :: i=1
Do i=1,N
A(i)=i
end do
call dscal(N,x, A, 1)

x=dasum(N,A,1)

END PROGRAM MAIN

我用命令编译

gfortran   test.f90  -o test -O1  -I /usr/include/ -L /usr/lib  -lblas

虽然我调用子例程dscal没问题，但是函数dasum

While I have no problem calling the subroutine dscal I get the following error for the function dasum

test.f90:15.2:

x=dasum(N,A,1)
1
Error: Function 'dasum' at (1) has no IMPLICIT type

我应该包括一个定义BLAS功能的文件吗?

Should I include a certain file to define the BLAS functions?

推荐答案

对于函数，您需要手动指定返回值(如果感觉很豪华，还可以选择external):

For functions, you need to manually specify the return value (and if you are feeling posh, optionally an external):

real*8,external :: dasum

---

此外，请不要使用real*8.它不符合标准，不便于移植并且令人困惑.而是使用kind参数定义精度，例如:

---

Additionally, please don't use real*8. It is not Standard-conforming, not portable and quite confusing. Instead use the kind parameter to define the precision, e.g.:

real(kind=kind(1.d0))

之类的.如果可以使用ISO_Fortran_env module，请使用其常量REAL32和REAL64.

or the like. If you can use the ISO_Fortran_env module, use its constants REAL32 and REAL64.

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