How to confirm the x-axis parameter of fimplicit's picture

a=0.336;
Ta=9.476;
Te=1.208;
Tw=1.498;
    eqh=[0.661,0.619,0.568];
    ex=[-1.240,-1.346,-1.441];
    en=-ex;
    ey=[0.376,0.705,0.968];
    eqx=[-0.309,-0.357,-0.392];
    eh=[1.594,1.583,1.545];
    exqh=en.*eqh+eqx.*eh;
    eyqh=[0.642,0.78,0.897];
syms bt Td;
Kp=1./bt;
Ki=1./(bt.*Td);

a4=a*Ta*Te^2;
a3=Ta*Tw.*eqh+a*Te^2.*en+a*Te^2.*Kp.*ey;
a2=a*Te^2.*Ki.*ey+Ta+Tw.*exqh-Kp.*Tw.*eyqh;
a1=en+Kp.*ey-Ki.*Tw.*eyqh;
a0=Ki.*ey

for i=1:3
    fimplicit(a1(i)*a2(i)*a3(i)-a1(i)^2*a4-a0(i)*a3(i)^2==0)
    hold on
end

I get a picture from the codes above, but I can confirm x-axis' name. Is it bt or Td?

Answer 1

[Walter Roberson]

fimplicit uses symvar(). The first variable output is used as the x axes.

symvar sorts the variable names according to byte values - so A before a and a10 before a2

T sorts before b so Td would be your x axes