Man page - fcmatrixrotate(3)

Packages contains this manual

Package: libfontconfig-doc
apt-get install libfontconfig-doc

Documentations in package:

FcMatrixRotate - Rotate a matrix

#include <fontconfig/fontconfig.h>

void FcMatrixRotate (FcMatrix * matrix , double cos , double sin );

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