Solving a two unknown function

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Thierry
Thierry 2014-7-21
回答： Thierry 2014-7-22
Is this possible with a two unknown function and a solve function to have all the couples of points that make Z=0 I mean how can I do
syms x;syms y;
Z=f(x,y);
S=solve(Z,(x,y));
S
and then get in the command window have : ans: S= [x(solution),y(solution)] or [x(solution1),y(solution1)]...

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采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2014-7-21
syms x y
z=x^2+2*y
sol=solve(z)

更多回答（1 个）

Thierry
Thierry 2014-7-22
Look, I tried to do what you say in my program here is the code (with matlab 7):
clear all; close all; clc;
U=400.0; S=120000; Phi=acos(1.0); P=S*cos(Phi); Q=S*sin(Phi);
I=S/(U*sqrt(3)); Zn=(U^2)/S; delta=20.0;
%%%%%%
syms Xd; syms Xq;
E1=sqrt(((U+Xq*I*sin(Phi))^2)+(Xq*I*cos(Phi))^2);
Eaf=(1/(2-Xq))*(E1+U*cos(delta)-(Xq/Xd)*U*cos(delta));
z=(-(3/2)*(U*Eaf/Xd)*sin(delta)+((U*U*(Xd-Xq))/(2*Xd*Xq))*sin(2*delta))-P;
S=subs(solve(z))
and what I get is a solution that is expressed with Xq variable and no Xd (and I know cause I've ploted it, that not all Xq points satisfy z equation)

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