Re: having difficulty using a for loop to solve an equation

[Thomas D. Dean]

On 06/19/2017 10:17 PM, Kire Pudsje wrote:
> On Tue, Jun 20, 2017 at 2:26 AM, shankara naryana 
> <address@hidden <mailto:address@hidden>> wrote:
>
>     got rid of i and j my code looks like this:
>
>     %Vectorization
>     clc;
>     clear;
>     a=[1 2 3 4 5];      %array created per spec
>     x=a;                %array created per spec
>     b=[-2 -1 0 1 2];    %array created per spec
>     y=5-2.*b;           %array created per spec
>     z=(y+x).^3;         %formula to be solved in loop
>     for m=a
>        t=z
>     end
>
>
> Actually you already wrote the vectorized form. There is no need for the 
> for loop anymore
> For the for loop solution, you would need to calculate the solution for 
> each index separately.
>
> I do not know if my other mail came through. There are network problems 
> in the Netherlands.
> But I think the assignment is ill-formed.
> Purely from a methematical perspective, only z_1 and z_2 are defined.

It appears this assignment is to demonstrate two ways to calculate the 
cube of the sum.

x = [1 2 3 4 5];
b=[-2 -1 0 1 2];
% Loop to calculate y
for idx = 1:size(b,2)
  y(idx) = 5 - 2 * b(idx);
endfor
% Loop to calculate z
for idx = 1:size(y,2)
  z(idx) = ( x(idx) + y(idx) ) ^ 3;
endfor

% vector method
x = 1:5;
y = ( 5 - 2 .* [-2:2] );
z = ( x + y ) .^ 3;

%Or, simply
z = ( [1:5] + ( 5 - 2 .* [-2:2] ) ) .^ 3

Tom Dean