How to add to index in for loop?

I am converting Python to Matlab. Here is Python code.

1. collocation points

xc=np.zeros((numPanels,1))

yc=np.zeros((numPanels,1))

for i in range(numPanels):

    xc[i]=(xp[i]+xp[i+1])/2
    yc[i]=(yp[i]+yp[i+1])/2

Here is my Matlab code...

% collection of points xc = zeros(numPanels, 1);

yc = zeros(numPanels, 1);

for k = numPanels

   xc(k) = (xp(k) + xp(k+1))/2

   yc(k) = (yp(k) + yp(k+1))/2
end

xp and yp are arrays. I am trying to add 1 to the second index of xp and yp, where it says xp(k+1) and yp(k+1). Would I need to make another for loop for the indexing that is being added to 1?

Answer 1

[KSSV]

xc = zeros(numPanels, 1);
yc = zeros(numPanels, 1);

for k = 1:numPanels-1

      xc(k) = (xp(k) + xp(k+1))/2
      yc(k) = (yp(k) + yp(k+1))/2
  end

You are in MATLAB..you can avoid loops here.

xc = (xp(1:end-1)+xp(2:end))/2 ;
yc = (yp(1:end-1)+yp(2:end))/2 ;

But the problem is size of xc and yc will be one less then xp and yp.

[Zach Dunagan]

That is fine. Why doesn't this work? I can only see the last value in the array.

% attaching/flipping xp and yp to the 66th % of the zero array

xp(66:end) = flipud(xp(1:numPanels/2));

yp(66:end) = -flipud(yp(1:numPanels/2));

% collocation points

 xc = zeros(numPanels, 1);

 yc = zeros(numPanels, 1);
for k = numPanels

   xc(k) = (xp(k) + xp(k+1))/2;

   yc(k) = (yp(k) + yp(k+1))/2;

end