Question

所以这是我的代码，它使用拉普拉斯的扩展递归计算矩阵的行列式。当我打印答案时，它以正确的格式打印，但数字不正确。我不知道为什么，希望你们比我更了解。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

/* Define a determinant for a certain matrix and dimension size*/
double det(double **mattemp, int size);

/*Find the values for our matrix and it's dimension*/
int main(int argc, char* argv[])
{
FILE         *input;
int          i, j, pos;
int          dim=1;
double       **matrix;

/*Open File*/
input = fopen("matrix.dat", "r");

/*Check file isn't NULL, if good find the no of lines and hence dimensions*/
if( (input != (FILE*) NULL) )
{
    while (EOF != (pos = fgetc(input)))
    {
        if (pos == '\n')
        {
            ++dim;
        }
    }
}
else
{
    printf("********************\n");
    printf("Could not open file!\n");
    printf("********************\n");
    return(EXIT_FAILURE);
}

/*Close and reopen file and set the matrix*/
fclose(input);
input = fopen("matrix.dat", "r");
matrix=(double**)malloc(dim*sizeof(double));

/*Fill the matrix with values from the file*/
for(i=0; i<dim; i++) 
{ 
    matrix[i]=(double*)malloc(dim*sizeof(double));
}
for(i=0; i<dim; i++)
{
    for(j=0; j<dim; j++)
    {
        fscanf(input, "%lf", &matrix[i][j]);
    }
}

/*Close the file*/
fclose(input);

/*Print the matrix*/
for(i=0; i<dim; i++)
{
    printf("| ");
    for(j=0; j<dim; j++)
    {
        printf("%lf ", matrix[i][j]);
    }

    if(i != dim/2)
    {
        printf("|\n");
    }
    else
    {
        printf("| = %lf \n", det(matrix, dim) );
    }
}
return(EXIT_SUCCESS);
}


double det(double **mattemp, int size) 
{   
double  dettemp, **temp;    
int     j, itemp, jtemp, jcurr;
double  column[size];

dettemp = 0;

if(size==1)
{
    dettemp = mattemp[0][0];
}
else if(size==2)
{
    dettemp = ((mattemp[0][0]*mattemp[1][1])-(mattemp[0][1]*mattemp[1][0]));
}
else
{
    for (j=0; j<size; j++) 
    {

        temp = malloc((size-1)*sizeof(*temp)); 

        for(itemp=0; itemp<(size-1); itemp++)
        {

            temp[itemp]=malloc((size-1)*sizeof(double*));
        }

        for(itemp=1; itemp<size; itemp++)
        {

            jtemp=0;

            for(jcurr=0; jcurr<size; jcurr++)
            {


                if(jcurr==j)
                {
                    continue;
                }

                temp[itemp-1][jtemp] = mattemp[itemp][jcurr];
                jtemp++;
            }

        }

        dettemp += (mattemp[0][j]*pow(-1,j)*det(temp, size-1));
    }   

    return(dettemp);
}
}

Answer 1

return(dettemp)中的det()放错地方了。

功能需要结束

  }
  return (dettemp);
}

来自代码的奇怪输出计算矩阵的行列式

1 个答案: