Hello! I am curious if this is possible. Say I write a function function F = func(x) F(1) = x(1)-cos(x(2)); F(2) = x(2)-cos(x(1)); end Now every time I call on this function it calculates the RHS of the equation and gives an output for F. Now if I had a ton of calculations before F that I don't want Matlab to constantly repeat, all I want is the last statement F. An example would be function F = func(x) % I send the x vector in order to get boundary conditions BC = Boundaries(x); % Now BC is a function with equations like BC(1) = x(1)+x(2)... etc F(1) = BC(1); F(2) = BC(2); end I want to use the function F(1) = x(1)+x(2), and not have to constantly send x to BC to "create" those equations.

Create function output seperately

Guillaume 2018-9-11

编辑：Guillaume 2018-9-11

I'm afraid I don't really understand what you're asking. What does to "create" those equations actually mean?

You can pass a function to use to another function if that's what you're after (i.e. you could pass different BC functions to func).

Kristoffer Lindvall 2018-9-11

Yes, the point is that every time I call on func(x) Matlab sends the x values to BC as well, and then to F. I would like to be able to create functions somewhere else once, and then set F equal to those functions, then have Matlab only evaluate F.

Imagine if the BC function takes a lot of CPU time to create the equations x(1)+x(2)... etc. I only want the result of BC. I don't want to go through the process of making BC. As far I have understood it, Matlab goes through BC every time I need to evaluate F. Even if I create BC somewhere else, it still goes through BC and all that that function has inside it to output a result.

I think the problem is that the function isn't creating equations, but more like a path that x values go through. This is really hard to explain I apologize.

Dennis 2018-9-11

在 MATLAB Online 中打开

You can create BC once and then pass it to func:

BC=Boundaries(2); %creating BC once
F=func(1:3,BC);
function BC=Boundaries(x)
BC=1:3+x; %some heavy calculations
end
function F=func(x,BC) %passing BC aswell
F(1)=BC(1)+x(2);
end

Stephen23 2018-9-11

编辑：Stephen23 2018-9-11

Then why not just move Boundaries outside of func and calculate it only once?

Guillaume 2018-9-11

Still not entirely clear on what is being asked, not helped by the imprecise terms used. You don't make functions. Functions don't create equations. You call a function with some inputs and it returns some outputs.

In addition to what has already been suggested, since R2017a, there is also the possibility of memoizing a function, a technique that caches the results of a function that is expensive to run so that it is only run if different inputs are provided. No idea, if that's what you're after.

Create function output seperately

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