Solve f(x) with mex files

Hello together,

i have the following problem.

An Matlab add-in gives me (via mex files) the possibility to generate Steam-Properties

e.g. function xs_ph_97(p,h) gave me the xs value of the steam.

So i have the following problem:

The i need to solve the function F(x) = (xs_ph_97(x,h) == 0,5).

When i create a script with

syms f(x)
f(x) = (xs_ph_97(x,h) == 0,5)

I get following error:

!x_ph_97: unreasonable type or size of argument 1!

Can somebody help me

Best regards

Answer 1

[Walter Roberson]

h = some appropriate value
x0 = initial value of x to check
Fx = fzero(@(x) xs_ph_97(x,h) - 0.5, x0);

This is not a function because there is a single x solution (or one solution for each h value): Fx will be the x that solves xs_ph_97(x,x) == 0.5

[Matthias Stark]

Thank you very much, the solver is working now Best regards