%線性方程組的符號解例5.8正弦穩態
syms z1 z2 z3 us
a=sym('[z1+z2,-z2;-z2,z2+z3]')
b=sym('[us;0]')
x=a\b
x1=subs(x,{z1,z2,z3,us},{j*3,5,-j*2,7.8*exp(160*j*pi/180)})
x11=abs(x1),x12=angle(x1)*180/pi