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/* 
File: MATRIX2D.C 
 
Basic 2D-matrix implementation in ANSI-C. 
 
C. Valens 
 
Created     : 05/09/1999 
Last update : 29/09/1999 
*/ 
 
 
#include "matrix2d.h" 
#include  
#include  
 
 
/* 
 * Allocate memory for a two-dimensional RxC matrix. 
 * Returns NULL on failure. 
 */ 
matrix_2d *matrix_2d_create(int r, int c)//创建一个行为r，列为c的二维矩阵的指针 
{ 
  int row; 
  matrix_2d *m;//建立二维矩阵的指针 
 
  m = malloc(sizeof(matrix_2d)); 
 
  if (m!=NULL) { 
    m->row = r; 
    m->col = c; 
    m->m = malloc(r*sizeof(element_type*)); 
    if (m->m==NULL) return NULL; 
    for (row=0; rowm[row] = malloc(c*sizeof(element_type)); 
      if (m->m[row]==NULL) return NULL; 
    } 
  } 
 
  return m; 
} 
 
 
/* 
 * Destroy a matrix. 
 */ 
void matrix_2d_destroy(matrix_2d *m)//删除二维矩阵 
{ 
  int row; 
  for (row=0; rowrow; row++) { 
    free(m->m[row]); 
  } 
  free(m); 
} 
 
 
/* 
 * Set all matrix elements to zero. 
 */ 
void matrix_2d_clear(matrix_2d *m)//对矩阵清0 
{ 
  int row, col; 
 
  for (row=0; rowrow; row++) { 
    for (col=0; colcol; col++) { 
      m->m[row][col] = 0; 
    } 
  } 
} 
 
/* 
 * Display a matrix. 
 */ 
void matrix_2d_write(matrix_2d *m)//打印出矩阵的值 
{ 
  int row, col; 
  for (row=0; rowrow; row++) { 
    for (col=0; colcol; col++) { 
      printf("%3d",m->m[row][col]); 
    } 
    printf("\n"); 
  } 
} 
 
 
/* 
 * Returns max(abs(matrix)), the absolute maximum value of a matrix. 
 */ 
element_type matrix_2d_abs_max(matrix_2d *m)//输出二维矩阵的绝对值的最大值 
{ 
  int row, col; 
  element_type max = 0; 
 
  for (row=0; rowrow; row++) { 
    for (col=0; colcol; col++) { 
      if (abs(m->m[row][col])>max) max = abs(m->m[row][col]); 
    } 
  } 
 
  return max; 
}