How to recursively reduce the function arguments
3 views (last 30 days)
Show older comments
Is there a way to create a function with one less argument dynamically? Basicly I'd like to find a way to do the following recursively or in a loop.
f4 = @(x1,x2,x3,x4) f5(x1, x2, x3, x4, 1);
f3 = @(x1,x2,x3) f4(x1, x2, x3, 1);
...
f1 = @(x1) f2(x1, 1);
r = f1(1)
function r = f5(x1, x2, x3, x4, x5)
r = x1 + x2 + x3 + x4 + x5
end
2 Comments
David Hill
on 9 Nov 2021
Very confusing. An example would be helpful. It seems to me that r=f1=f2=f3=f4=f5=4+x1; which equals 5 in the example above (x1=1). Not sure what you are trying to do, but it is not wise to have all those variables.
Accepted Answer
Stephen23
on 9 Nov 2021
It can be done with VARARGIN:
N = 5;
C = cell(1,N);
C{N} = @f5;
for k = N-1:-1:1
C{k} = @(varargin) C{k+1}(varargin{:},1);
end
C{1}(1)
function r = f5(x1, x2, x3, x4, x5)
r = x1 + x2 + x3 + x4 + x5;
end
More Answers (2)
Jan
on 9 Nov 2021
This should work with str2func and eval.
This is such a cruel programming technique, that I recommend not to use it. Such meta-programming for creating code dynamically is hard to debug and Matlab's JIT acceleration cannot work. This can slow down the code by a factor 100 compared to some code, which avoid the dynamic creation of variables and functions.
1 Comment
Adam Danz
on 9 Nov 2021
The function string could also be parsed to remove the penultimate input and then converted back to a function handle without using eval. But I still think there's a better approach.
Adam Danz
on 9 Nov 2021
x1 = rand(1);
x2 = rand(1);
x3 = rand(1);
x4 = rand(1);
p = [x1, x2, x3, x4];
f5([p,1])
p = [x1, x2, x3];
f5([p,1])
p = [x1, x2];
f5([p,1])
function f5(varargin)
sum([varargin{:}])
end
0 Comments
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!