###### tags: `code`

# C14086028 homework-5

#include<stdio.h>
#include<stdlib.h>
#define I 4
#define J 4
double matrixmul(double [I][J],double [I][J]);
int main() {
	double A[I][J] = { {0.1,0.2,0.4,0.3},{0.5,0.2,0.1,0.2},{0.3,0.4,0.2,0.1},{0.15,0.25,0.2,0.4} };
	double B[I][J] = { {0} };

	/*give value of entries of B[I][J]*/
	for (int a = 0; a < I; a++) {
		for (int b = 0; b < J; b++) {
			B[a][b] = A[a][b];
		}
	}
	/*print initial value of entries of A[][] and print n-th power of A[][] */
	printf("the matrix A (1-th power A) is \n");
	for (int b = 0; b < I; b++) {
		for (int c = 0; c < J; c++) {
			printf("%3.20lf\t", B[b][c]);
		}
		printf("\n");
	}
	for (int a = 1; a < 15; a++) {
		matrixmul(A,B);
		printf("the matrix %d -th power of A is \n\n",a+1);
		for (int b = 0; b < I; b++) {
			for (int c = 0; c < J; c++) {
				printf("%3.20lf\t", B[b][c]);
			}
			printf("\n");
		}
		printf("\n");
	}
	system("pause\n");
	return 0;
}
double matrixmul(double A[I][J], double B[I][J]) {
	double C[I][J] = { { } };
	for (int k = 0; k < I; k++) {
		for (int i = 0; i < I; i++) {
			C[k][i] = 0;
			for (int j = 0; j < J; j++) {
				C[k][i] += A[k][j] * B[j][i];
			}
		}
	}
	for (int i = 0; i < I; i++) {
		for (int j = 0; j < J; j++) {
			B[i][j] = C[i][j];
		}
	}
	return 0;
}