Backward Loop Question- Help

I am trying to get the code to start at a certain value lets say 80 and start counting down from there. But I am struggling to see where to put this information into my code to make this happen.

 xdt3 = 5;

 xt03 = 0;

 xtf3 = 60;

 xt3 = xtf3:-xdt3:xt03;

 x3 = zeros(1,13);

 for i = length(xt3):-1:2

      x3(i-1) = x3(i) - ((5 - (4 /50)*x3(i)))*xdt3;

 end

[Stephen23]

Duplicate:

http://www.mathworks.com/matlabcentral/answers/266957-for-loop-backwards-help

[WhatIsMatlab-]

It is a different question. Similar titles

Answer 1

[Star Strider]

You have to make the appropriate modifications to my previous code to make your new step size work:

xdt3 = 5;

xt03 = 0;

xtf3 = 60;

xt3 = xtf3:-xdt3:xt03;

x3 = zeros(1,13*xdt3);

for i = xtf3:-xdt3:xdt3+1

      x3(i-xdt3) = x3(i) - ((5 - (4 /50)*x3(i)))*xdt3;

end

This runs, so you have to decide if it gives you the result you want. Note that MATLAB will skip the indices you do not address, resulting in a significant number of zero

values in your vector. You may also want to change the initial line in the for loop to:

for i = xtf3+xdt3:-xdt3:xdt3+1

[WhatIsMatlab-]

Thank you!! I understand what you are saying

[Star Strider]

My pleasure!

Also, if you want only the non-zero values, this works:

X3 = x3(x3~=0);