diff options
Diffstat (limited to 'libdimension/geometry.c')
| -rw-r--r-- | libdimension/geometry.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/libdimension/geometry.c b/libdimension/geometry.c index 030cd68..8ebc3d9 100644 --- a/libdimension/geometry.c +++ b/libdimension/geometry.c @@ -65,7 +65,7 @@ dmnsn_rotation_matrix(dmnsn_vector theta) } axis = dmnsn_vector_normalize(theta); - /* Shorthand to make dmnsn_matrix_construct call legible */ + /* Shorthand to make dmnsn_matrix_construct() call legible */ s = sin(angle); t = 1.0 - cos(angle); @@ -123,7 +123,13 @@ dmnsn_matrix_inverse(dmnsn_matrix A) double Pdet = A.n[0][0]*A.n[1][1] - A.n[0][1]*A.n[1][0]; if (Pdet == 0.0) { - /* If we can't invert P, try a more generic algorithm */ + /* If we can't invert P, try a more generic algorithm; this is very + unlikely, but not impossible, eg. + ( 1 1 0 0 ) + ( 1 1 1 0 ) + ( 0 1 1 0 ) + ( 0 0 0 1 ) + */ return dmnsn_matrix_inverse_generic(A); } @@ -146,6 +152,7 @@ dmnsn_matrix_inverse(dmnsn_matrix A) PiQ = dmnsn_matrix2_mul(Pi, Q); RPiQ = dmnsn_matrix2_mul(R, PiQ); + /* Calculate the partitioned inverse */ SS = dmnsn_matrix2_inverse(dmnsn_matrix2_sub(S, RPiQ)); RR = dmnsn_matrix2_negate(dmnsn_matrix2_mul(SS, RPi)); QQ = dmnsn_matrix2_negate(dmnsn_matrix2_mul(PiQ, SS)); |