有关fortran位数取舍问题

pasuka

本站的教学视频都看过了？
看过三遍还是一知半解，那是教学视频做得不好；一遍都没看过，那是lz人生的重大遗憾！
言归真正：
首先，小数点后的第二位就有差别，岂能熟视无睹？
其次，硬件与编译器是否支持呢？
https://gcc.gnu.org/onlinedocs/g ... 005fFORTRAN_005fENV

REAL32, REAL64, REAL128:
Kind type parameters to specify a REAL type with a storage size of 32, 64, and 128 bits. It is negative if a target platform does not support the particular kind. (Fortran 2008 or later.)

REAL_KINDS:
Default-kind integer constant array of rank one containing the supported kind parameters of the REAL type. (Fortran 2008 or later.)

pasuka

补充一个gfortran的四精度扩展支持
https://gcc.gnu.org/onlinedocs/g ... l#Q-exponent-letter

6.1.8 Q exponent-letter
GNU Fortran accepts real literal constants with an exponent-letter of Q, for example, 1.23Q45. The constant is interpreted as a REAL(16) entity on targets that support this type. If the target does not support REAL(16) but has a REAL(10) type, then the real-literal-constant will be interpreted as a REAL(10) entity. In the absence of REAL(16) and REAL(10), an error will occur.