/* information matrix for F2 with selective genotyping */

h: matrix([1+3*J,2*(1-J),(1-J)],
	  [2*(1-J),4*(1+J),2*(1-J)],
	  [(1-J),2*(1-J),1+3*J]);

/* get determinant of info matrix */

ratsimp(determinant(h/16));

/* get inverse of info matrix */

ratsimp(invert(h/16));