# How to go around infinite recursions

3 views (last 30 days)
Albert Garcia on 5 Nov 2019
Answered: Albert Garcia on 15 Nov 2019
Hi. I have a series of functions that go Weight_Approx_1 -> Geometric_Approx -> Weight_Approx_2 . I would like for the Weight_Approx_2 to feed back in to Weight_Approx_1 so it can act as the new input. I can do this so well that I get an infinite loop without trying. How do I get a loop like this to return a final value from the Weight_Approx_2 program after a number of iterations I choose?
In other words, how do I rewrite a series of functions like below such that I control how many times f_c gets run? Once int == 2, it'll just be an infinite loop
function a = fa
for int = (1:10)
if int = 1
a = 1;
else
a = fc;
end
end
end
function b = fb
b = fa*2
end
function c = fc
c = fb + 1;
end

Albert Garcia on 15 Nov 2019
I just redesigned the whole program for this program to work.

Richard Brown on 5 Nov 2019
I'm not sure the code you've written describes what you intend. It's going to create an unterminated recursion that will cause an error very quickly.
Can you describe in words a little more clearly what you mean? Why are you using recursion at all? Why not something like:
x = 1; % whatever your initial estimate of the "thing" is
for k = 1:max_iterations
a = weight_approx_1(x);
b = geometric_approx(a);
x = weight_approx_2(b);
end
Richard Brown on 7 Nov 2019
Sorry for taking a while to get back to you. Just looking at it now - what do you mean by "value output from WEIGHT_SIZING is seen in all the other files". The function WEIGHT_SIZING has no inputs or global variables, so I don't see how running this again will help ...
perhaps you could step me through the actual calculation you want performed (what variables need to be iterated)?
Albert Garcia on 7 Nov 2019
So the function WEIGHT_SIZING has an output of weight. This value is an input to every other function, and once this value has propagated through all the other functions, one of the outputs of WEIGHT_APPROXIMATION is also a weight. I would like this weight to cycle back to that WEIGHT_SIZING program and become the new output of WEIGHT_SIZING or the new input to all the other functions.
I inserted a picture of what kind of loop I would like. The writing in purple is what I have already, a straight flow from WEIGHT_SIZING to other programs that feed into WEIGHT_APPROXIMATION. What I would like is one of the loops in gray or blue, with the gray being a loop that gives me an infinite recursion and the blue seeming to be one that can't be done. The gray is one where I have a conditional in the WEIGHT_SIZING program that swaps the value from the method in which this program calculates weight to the value from the WEIGHT_ALLOCATION program, but because the second program is a function of the first, I get an infinite recursion. The blue one is where the value of WEIGHT_ALLOCATION is directly plugged in to the functions; whereever I have a function call for WEIGHT_SIZING, it calls for WEIGHT_ALLOCATION instead, bypassing the whole infinite recursion nonsense, but I don't know how to do that.

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