Matrix d2 using coeff as given in cramer 's rule
double d2 [ 3 ] [ 3 ] = { { coeff [ 0 ] [ 0 ] , coeff [ 0 ] [ 3 ] , coeff [ 0 ] [ 2 ] } , { coeff [ 1 ] [ 0 ] , coeff [ 1 ] [ 3 ] , coeff [ 1 ] [ 2 ] } , { coeff [ 2 ] [ 0 ] , coeff [ 2 ] [ 3 ] , coeff [ 2 ] [ 2 ] } , } ;