It looks like somebody implemented a QUATPLOT(A,B,C,D,marker,string) function in Matlab: Percentage values (A,B,C,D) are transformed into xyz coordinates, allowing plotting % of data in the tetrahedron. Source code and documentation can be found at https://de.mathworks.com/matlabcentral/fileexchange/68595-3d-plotting-in-a-four-variable-system-quatplot