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033_28.1_LU.c
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033_28.1_LU.c
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#include<stdio.h>
#include<stdlib.h>
#include<math.h>
struct TwoM {
int l[4][4];
int u[4][4];
};
struct OneM
{
int c[4][4];
};
void printA(int a[][4]) {
for (int i = 0; i < 4; i++)
{
for (int j = 0; j < 4; j++)
{
printf("%2d ", a[i][j]);
}
printf("\n");
}
}
OneM *multipal(int a[][4], int b[][4]) {
OneM *temp = (OneM *)malloc(sizeof(OneM));
for (int i = 0; i < 4; i++)
{
for (int j = 0; j < 4; j++)
{
for (int k = 0; k < 4; k++)
{
temp->c[i][j] += a[i][k]*b[k][j];
}
}
}
return temp;
}
TwoM *LU(int a[][4]) {
TwoM *lu = (TwoM *)malloc(sizeof(TwoM));
for (int i = 0; i < 4; i++)
{
for (int j = 0; j < 4; j++)
{
lu->u[i][j] = 0;
if(i == j) lu->l[i][j] = 1;
else lu->l[i][j] = 0;
}
}
for (int k = 0; k < 4; k++)
{
lu->u[k][k] = a[k][k];
for (int i = k+1; i < 4; i++)
{
lu->l[i][k] = a[i][k]/lu->u[k][k];
lu->u[k][i] = a[k][i];
}
for (int i = k+1; i < 4; i++)
{
for (int j = k+1; j < 4; j++)
{
a[i][j] = a[i][j]-lu->l[i][k]*lu->u[k][j];
}
}
}
return lu;
}
void main() {
int a[4][4] = {{2,3,1,5},
{6,13,5,19},
{2,19,10,23},
{4,10,11,31}};
printf("A:\n");
printA(a);
puts("");
TwoM *result = LU(a);
printf("L:\n");
printA(result->l);
puts("");
printf("U:\n");
printA(result->u);
puts("");
}