Function File: W = gram (sys, mode)

Function File: Wc = gram (a, b)

gram (sys, "c") returns the controllability gramian of the (continuous- or discrete-time) system sys. gram (sys, "o") returns the observability gramian of the (continuous- or discrete-time) system sys. gram (a, b) returns the controllability gramian Wc of the continuous-time system $d\times /dt\; =\; a\times \; +\; b\; u$; i.e., Wc satisfies $a\; Wc\; +\; m\; Wc’\; +\; b\; b’\; =\; 0$.