gfortran 编译器错误:求幂结果超出 INTEGER(4) 的范围 [英] gfortran compiler Error: result of exponentiation exceeds the range of INTEGER(4)

问题描述

我在 fortran 中有这一行，但标题中出现编译器错误.dFeV 是一维实数数组.
dFeV(x)=R1*5**(15) * (a**2) * EXP(-(VmigFe)/kbt)
作为记录，变量名是继承的，不是我的错.我认为这是一个问题，因为没有内存空间来计算右侧的值，然后我将其存储在左侧作为真实值(这将有足够的空间)，但我不知道如何为此分配更多空间计算.

I have this line in fortran and I'm getting the compiler error in the title. dFeV is a 1d array of reals.
dFeV(x)=R1*5**(15) * (a**2) * EXP(-(VmigFe)/kbt)
for the record, the variable names are inherited and not my fault. I think this is an issue with not having the memory space to compute the value on the right before I store it on the left as a real (which would have enough room), but I don't know how to allocate more space for that computation.

推荐答案

问题出现是因为您的计算的一部分是使用 integer(4)整数算术 完成的>.该类型的上限为 2^31-1 = 2147483647 而您的中间结果 5^15 = 30517578125 稍大(感谢@evets 评论).

The problem arises as one part of your computation is done using integer arithmetic of type integer(4). That type has an upper limit of 2^31-1 = 2147483647 whereas your intermediate result 5^15 = 30517578125 is slightly larger (thanks to @evets comment).

正如您的问题所指出的:您将结果保存在一个实变量中.因此，您可以使用 real 数据类型:5.0**15 计算该指数.您的公式最终将如下所示

As pointed out in your question: you save the result in a real variable. Therefor, you could just compute that exponentiation using real data types: 5.0**15. Your formula will end up like the following

dFeV(x)= R1 * (5.0**15) * (a**2) * exp(-(VmigFe)/kbt)

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请注意，integer(4) 不必是每个处理器的相同实现(感谢@IanBush).这只是意味着对于某些特定机器，上限可能与 2^31-1 = 2147483647 不同.

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Note that integer(4) need not be the same implementation for every processor (thanks @IanBush). Which just means that for some specific machines the upper limit might be different from 2^31-1 = 2147483647.

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