问题描述
用Fortran 90编写的程序手册说:所有的实际变量和参数都是以64位精度指定的(即 real * 8 )。 p>根据,单精度对应到32位精度,而双精度对应于64位精度,所以程序显然使用双精度。
但 real * 8 是什么意思?
我认为 8 意味着8位数字在小数点后面。然而,似乎表示,单精度通常提供6-9位数,而通常提供15-17位数字。这是否意味着64位精度语句与 real * 8 不一致?
8表示数据类型使用的字节数。
所以,一个32位整数是整数* 4 沿着同一行。
快速搜索发现,其中包括:
$ b
和
The manual of a program written in Fortran 90 says, "All real variables and parameters are specified in 64-bit precision (i.e. real*8)."
According to Wikipedia, single precision corresponds to 32-bit precision, whereas double precision corresponds to 64-bit precision, so apparently the program uses double precision.
But what does real*8 mean?
I thought that the 8 meant that 8 digits follow the decimal point. However, Wikipedia seems to say that single precision typically provides 6-9 digits whereas double precision typically provides 15-17 digits. Does this mean that the statement "64-bit precision" is inconsistent with real*8?
The 8 refers to the number of bytes that the data type uses.
So a 32-bit integer is integer*4 along the same lines.
A quick search found this guide to Fortran data types, which includes:
and
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