Matrix4x3 invertMatrix(const Matrix4x3 &m) {
double w[3][8];
for (int r = 0; r != 3; ++r) {
for (int c = 0; c != 4; ++c) {
w[r][c] = m(r, c);
w[r][c+4] = (r == c) ? 1.0 : 0.0;
}
}
if (w[0][0] == 0.0) {
if (w[1][0] != 0.0)
swapRows(w[0], w[1]);
else
swapRows(w[0], w[2]);
}
divideRow(w[0], w[0][0]);
subtractRow(w[1], w[1][0], w[0]);
subtractRow(w[2], w[2][0], w[0]);
if (w[1][1] == 0.0)
swapRows(w[1], w[2]);
divideRow(w[1], w[1][1]);
subtractRow(w[0], w[0][1], w[1]);
subtractRow(w[2], w[2][1], w[1]);
divideRow(w[2], w[2][2]);
subtractRow(w[0], w[0][2], w[2]);
subtractRow(w[1], w[1][2], w[2]);
for (int r = 0; r != 3; ++r) {
w[r][7] = -w[r][3];
w[r][3] = 0.0;
}
Matrix4x3 result;
for (int r = 0; r != 3; ++r)
for (int c = 0; c != 4; ++c)
result(r, c) = float(w[r][c+4]);
return result;
}
int main()
{
/* Add your implementation here */
int i;
int j;
int size;
int colNum;
int rowNum;
char * pointless;
double ** mat;
char * input = getInput();
if(strIsNum(input)){
size = strtod(input, &pointless);//strToNum(input);
}
else
sizeError();
rowNum = size;
colNum = size + 1;
//Create matrix array
mat = malloc(sizeof(double *) * rowNum);
for(i = 0; i < size; i++){
mat[i] = malloc(sizeof(double) * colNum);
for(j = 0; j < colNum; j++){
input = getInput();
if((strlen(input) == 0)||!strIsNum(input))
printMissingEl(i, j );
else
mat[i][j] = strtod(input, &pointless);
}
}
printf("initial matrix\n");
printMatrix(rowNum, colNum, mat);
for(i = 0; i < rowNum; i++){
int maxPos = i;
//find the maximum value of abs(r[j][i]) where j >= i
for(j = i + 1; j < rowNum; j++){
if(fabs(mat[j][i]) > fabs(mat[maxPos][i])){
maxPos = j;
}
}
// this makes the pivot nonzero if possible
int isSingular = 1;
for(j = 0; j < rowNum; j++){
if(mat[i][j] != 0){
isSingular = 0;
break;
}
}
if(isSingular){
printf("Error: Matrix is singular\n");
exit(0);
}
printf("swapped %d and %d\n", i, maxPos);
swapRows(maxPos, i, mat);
printMatrix(rowNum, colNum, mat);
printf("row %d /= %f\n", i, mat[i][i]);
divideRow(i, colNum, mat);
printMatrix(rowNum, colNum, mat);
for(j = 0; j < rowNum; j++){
if(i != j){
printf("row %d -= %f row %d\n", j, mat[j][i], i);
makeZero(j, i, colNum, mat);
printMatrix(rowNum, colNum, mat);
}
}
}
for(i = 0; i < rowNum; i++){
printf("%f ",mat[i][size]);
}
printf("\n");
return 0;
}
