Function R = rotationmat3Dcoord(alpha,ordre) creates the matrix for rotation by alphax around the x-axis, alphay around the y-axis, and alphaz around the z-axis. The rotations are done in the given ordre. Given a point by vector [x y z]. Using the expanded column vector for it: P = [x; y; z; 1] The coordinates of the point after rotation, are given by the expanded column vector Q, by calculation with the matrix of rotation R: Q = R * P The input variable alpha = [alphax alphay alphaz] gives the rotation angles in degrees. A positive alphaA yields a rotation counter-clockwise, seen from a positive infinity position on the A-axis, for A = "x", "y" or "z". The input variable ordre is a 3-element vector, indicating along which axis the rotation is applied first, second or third. A zero in the variable indicates that no rotation along the respective axis is applied. If for example only a rotation along the z-axis is applied, one types: ordre = [0 0 1] (and then alphax and alphay are ignored). Try also: demo rotationmat3Dcoord Reference: Section "3. 3D Coordinate axes rotation matrices" from: "Rotation About an Arbitrary Axis in 3 Dimensions" by: Glenn Murray June 6, 2013 http://inside.mines.edu/fs_home/gmurray/ArbitraryAxisRotation/ visited 20160219 (c) 2026 fabien van mook 2026.08.20 release of this file within package "fvm-geometry" under GNU GPLv3+