loop with two variables

Hello,

I am trying to write a code to do a loop with two variables.

I am solving the characteristic equation of a polynomial using the command root and i am taking the eigenvalues.

I want to change two variables (a and b) and do a loop. For every value of b calculate the eigenvalues at the range of a.

For example for a=0:1:3

b=0:1:3

And finally give me the results in a seperate matrix or vector.

Currently i am using arrayfun but only for one variable(a)

How can i do it?

Thank you

Answer 1

[Walter Roberson]

avals=0:3;
bvals=0:3;
Numa=length(avals) ;
Numb=length(bvals) ;
Result=cell(Numa, Numb) ;
for aidx = 1:Numa
  a = avals(aidx) ;
  for bidx = 1:Numb
    b = bvals(bidx) ;
    Array=something involving a and b
    Result{aidx, bidx} = eig(Array) ;
  end
end

[Ilias Minas]

Thank you very much!

It worked!

[Ilias Minas]

Hi Walter,

I want to thank you first of all for your help.

I am using your answer and solved my hands.

However i want to ask you if its possible to do it with three variables. I tried to use the same code that you mentioned but its not working.

let my give you an example

For example for a=0:1:3

b=0:1:3

c=0:1:3

for a=0 and b=0 c=0:1:3

for a=1 and b=0 c=0:1:3 etc

I want all the possible compinations of a and b which are 4 in this case, to run in the whole range of c and have the result in a matrix or vector or cell array.

I would appreciate your help

Thank you again

[Walter Roberson]

av=0:1:3;
bv=0:1:3;
cv=0:1:3;
[A, B, C] = ndgrid(av, bv, cv);
result = arrayfun(@(a,b,c) FunctionOfThreeVariables(a,b,c), A, B, C)

If the function returns a non-scalar, then add 'uniform', 0 as an option to get a cell array of results.