main/src/georegression/geometry/ConvertRotation3D_F64.java
public static void setRotZ( double ang, DMatrixRMaj r ) {
		double c = Math.cos( ang );
		double s = Math.sin( ang );

		r.set( 0, 0, c );
		r.set( 0, 1, -s );
		r.set( 1, 0, s );
		r.set( 1, 1, c );
		r.set( 2, 2, 1 );
	}
public static void setRotZ( double ang, DMatrixRMaj r ) {
		double c = Math.cos( ang );
		double s = Math.sin( ang );

		r.set( 0, 0, c );
		r.set( 0, 1, -s );
		r.set( 1, 0, s );
		r.set( 1, 1, c );
		r.set( 2, 2, 1 );
	}
Sets the values in the specified matrix to a rotation matrix about the z-axis.

@param ang the angle it rotates a point by in radians.
@param r   A 3 by 3 matrix. Is modified.