请问双双精度变量赋值时后缀加什么？

pasuka

shrine 发表于 2017-11-9 13:48
感谢一直以来的帮助
再请教一个语法问题，行向量和矩阵中的一列相乘难道不是一个数么
为何这段代码说c的形 ...

首先，翻阅gfortran帮助文档
https://gcc.gnu.org/onlinedocs/g ... /MATMUL.html#MATMUL
MATMUL — matrix multiplication
Description:
Performs a matrix multiplication on numeric or logical arguments.
Standard:
Fortran 95 and later
Class:
Transformational function
Syntax:
RESULT = MATMUL(MATRIX_A, MATRIX_B)
Arguments:
MATRIX_A        An array of INTEGER, REAL, COMPLEX, or LOGICAL type, with a rank of one or two.
MATRIX_B        An array of INTEGER, REAL, or COMPLEX type if MATRIX_A is of a numeric type; otherwise, an array of LOGICAL type. The rank shall be one or two, and the first (or only) dimension of MATRIX_B shall be equal to the last (or only) dimension of MATRIX_A.
Return value:
The matrix product of MATRIX_A and MATRIX_B. The type and kind of the result follow the usual type and kind promotion rules, as for the * or .AND. operators.

显然根据文档不难发现，输入和输出变量的rank都不会小于1，那么Fortran里面的rank又是怎么定义的呢？


接着查看rank函数
https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gfortran/RANK.html#RANK
The return value is of type INTEGER and of the default integer kind. For arrays, their rank is returned; for scalars zero is returned.

Example:

[Fortran] 纯文本查看 复制代码

program test_rank
  integer :: a
  real, allocatable :: b(:,:)
  print *, rank(a), rank(b) ! Prints:  0  2
end program test_rank