Simple 3x3 matrix inverse code (C++)

Question

What\'s the easiest way to compute a 3x3 matrix inverse?

I\'m just looking for a short code snippet that\'ll do the trick for non-singular matrices, possibly using C

Answer 1

I have just created a QMatrix class. It uses the built in vector > container. QMatrix.h It uses the Jordan-Gauss method to compute the inverse of a square matrix.

You can use it as follows:

#include "QMatrix.h"
#include 

int main(){
QMatrix A(3,3,true);
QMatrix Result = A.inverse()*A; //should give the idendity matrix

std::cout<

The inverse function is implemented as follows:

Given a class with the following fields:

template class QMatrix{
public:
int rows, cols;
std::vector > A;

the inverse() function:

template 
QMatrix QMatrix:: inverse(){
Identity Id(rows); //the Identity Matrix as a subclass of QMatrix.
QMatrix Result = *this; // making a copy and transforming it to the Identity matrix
T epsilon = 0.000001;
for(int i=0;i0;--i){
    for(int j=i-1;j>=0;--j){
        T temp = Result(j,i);
        Id(j) = Id(j) - temp*Id(i);
        Result(j)=Result(j)-temp*Result(i);
    }
}

return Id;
}