CODEWITHSUNDEEP
matlab
Dan Dao
Dan Dao

Reputation: 31

Defining an anonymous function using a symbolic expression in a vector that's already defined

So here's the problem I'm having trouble with.

You solve for an expression using the symbolic engine, but it's parametrized by some z. Now you want to create a function for this expression with variable z.

Here's the code:

syms a1 a2 a4 b1 b2 b4 c1 c2 c4

[a1, a2, a4, b1, b2, b4, c1, c2, c4] = ...
    solve('a1 + a4 = 1', ...
    'a1*a4 - a2^2 = 0', ...
    'b1 + b4 = 7', ...
    'b1*b4 - b2^2 = 10', ...
    'c1*c4 - c2^2 = 55/4', ...
    'c1 + c4 = 8', ...
    'c1 = a1 + b1', ...
    'c2 = a2 + b2', ...
    'c4 = a4 + b4');

Now I can do something like 

a1 = @(z) 13/18 - (- (35*z^2)/81 + (280*z)/81 - 1925/324)^(1/2)/2 - z/18;

to define a1 to be the first entry of the vector a1 that was already defined...

But I want to instead to something like

a1 = @(z) a1(1)

and then be able to type a1(2) or a1(4) to plug in values for z into that expression.

How can I do this?

Upvotes: 0

Views: 125

Answers (1)

Dan Dao
Dan Dao

Reputation: 31

Ah, just browsing around stack exchange for related questions and the tweaked some code to find a solution:

f = @(t) subs(a1(1), 'z', t).

Upvotes: 1

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