Fortran函数中带有可选参数的分段错误 [英] Segmentation fault with optional arguments in Fortran functions

问题描述

我可以将Fortran可选参数与带有intent(in)和intent(inout)的子例程一起使用，但是通过函数，可选参数只能与intent(in)一起使用，对吗?使用intent(inout)，我在以下代码中遇到分段错误:

I can use Fortran optional argumenrs with subroutines with intent(in) and intent(inout), but with functions optional arguments work only with intent(in), right? With intent(inout) I get segmentation faults in the following code:

real function foo(x, tol) 
    real, intent(in) :: x
    real, optional, intent(inout) :: tol
    if( .not. present(tol) ) tol = 1e-6
    !...
end function foo

推荐答案

我发现了问题，即使在第四行(在tol = 1e-6中)不存在，我也使用了变量:

I found the problem, I used the variable even when not present on the fourth line (in tol = 1e-6):

real function foo(x, tol) 
    real, intent(in) :: x
    real, optional, intent(inout) :: tol
    if( .not. present(tol) ) tol = 1e-6
    !...
end function foo 

但是即使在不存在的情况下，我也想使用它并设置默认值，例如在C ++中，我们要做类似的事情

But I would like to use it even when not present and set a default value, like when in C++ we do something like that

double foo(double x, double tol=1e-6)

不幸的是，似乎在Fortran中是不可能的.

Unfortunately, it seems it is not possible in Fortran.

这篇关于Fortran函数中带有可选参数的分段错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！