MATLAB: Simplifying a series of non-linear equations as a function of specific variables

non-linearseries of equationssymbolic

If I have a series of non-linear equations: a=f(x,y,z,w), x=g(z,w), y=h(z,w), and I want to get a result a=F(x,y) (i.e. for matlab to substitute x,y in the original function with the corresponding functions that are dependent on z,w so that I can get a result for a that is only dependent on z,w). Is there a way for me to have Matlab do this?

ex. a=x+y^2+x*z+y*w*2, x=z^2, y=w+z would result in: a=z^2+(w+z)^2+z^3+z^2(w+z)

Best Answer

syms a x y w z
a=z+y^2+x*z+y*w*2;
a=subs(z+y^2+x*z+y*w*2,[x,y],[z^2,w+z])

Related Solutions

MATLAB: Plot surface from non-anonymus function

See if this does what you want —

function z = test(w)
    x = w{1};
    y = w{2};
    z = 2*x.^2 + 2*y.^2 +10*(1.1*y.^2 +3*x.^2).^0.5;
end
x = -10:10;
y = -15:5;
[W{1},W{2}] = ndgrid(x,y);
Z = test(W);
figure
surf(W{1},W{2},Z)
grid on

Note that I created ‘w’ as cell arrays to pass its elements as matrices. Other than that change, your function is as you wrote it.

MATLAB: Storing the inputs of a function on a structure (or cell or array)

d=struct('x',1,'y',2);
[z,w] = tempFun(d)
function [z,w] = tempFun(s)
    z = s.x+1;
    w = s.y+1;
end

Best Answer

Related Solutions

MATLAB: Plot surface from non-anonymus function

MATLAB: Storing the inputs of a function on a structure (or cell or array)

Related Question