man FcMatrixRotate (Fonctions bibliothèques) - Rotate a matrix
NAME
FcMatrixRotate - Rotate a matrix
SYNOPSIS
#include <fontconfig.h> void FcMatrixRotate (FcMatrix *matrix, doublecos, doublesin);
DESCRIPTION
FcMatrixRotate rotates matrix by the angle who's sine is sin and cosine is cos. This is done by multiplying by the matrix:
cos -sin sin cos
VERSION
Fontconfig version 2.3.2