复杂(8)的CABS(x)函数 [英] CABS(x) function for complex(8)

问题描述

是否存在双精度复数值的绝对值函数?当我尝试CABS()我得到

Is there an absolute value function for a complex value in double precision? When I try CABS() I get

            V(1,j) = R(j,j) + (R(j,j)/cabs(R(j,j)))*complexnorm2(R(j:m,j))

错误:(1)中对'cabs'的调用中参数'a'的类型应为 COMPLEX(4)，而不是COMPLEX(8)"

"Error: Type of argument 'a' in call to 'cabs' at (1) should be COMPLEX(4), not COMPLEX(8)"

我已经读过一个叫做CDABS()的函数，但是我不确定那是同一回事吗?

I have read there's a function called CDABS() but I wasnt sure if that was the same thing?

推荐答案

除了ABS()外，没有其他原因.内在过程的泛型已经在FORTRAN 77中提供.您可以将它们用于所有内在数字类型.

There is no reason using anything else than ABS(). Generics for intrinsic procedures were already present in FORTRAN 77. You can use them for all intrinsic numeric types.

如果要查看通用ABS()的可用特定功能表，请参见 https://gcc.gnu.org/onlinedocs/gfortran/ABS.html ，但它们仅在作为实际参数传递时才非常有用.您会看到CDABS()是非标准扩展名，我不建议使用它.

If you want to see the table of available specific functions of the generic ABS(), see https://gcc.gnu.org/onlinedocs/gfortran/ABS.html , but they are mostly useful only to be passed as actual arguments. You can see that CDABS() is a non-standard extension and I do not recommend to use it.

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