c++ - 查找 GSL 矩阵中的行数/列数？

Question

假设我有一些 gsl_matrix * A。我想编写一个函数来检索例如该矩阵中的行数，除了对象 A 本身之外无法访问其他任何内容。

示例:

int num_rows(gsl_matrix * A){
    //some operation(s) on A that find the number of rows in the matrix
    //store that number in an int r
    return r;
}

我可以写什么来为我做到这一点？

Answer 1

来自https://www.gnu.org/software/gsl/manual/html_node/Matrices.html

gsl_matrix 定义为:

typedef struct
{
  size_t size1;
  size_t size2;
  size_t tda;
  double * data;
  gsl_block * block;
  int owner;
} gsl_matrix;

还有

The number of rows is size1. The range of valid row indices runs from 0 to size1-1. Similarly size2 is the number of columns. The range of valid column indices runs from 0 to size2-1. The physical row dimension tda, or trailing dimension, specifies the size of a row of the matrix as laid out in memory.

因此，如果您想要 A 中的行数，那么您可以使用:

int num_rows(gsl_matrix * A){
    int r = A->size1;
    return r;
}