Calculate Matrix and then use previously calculated matrix in next iteration

I start with a set of values (1x50) and perform an equation. I then want the calculated values to be used in the next iteration of the equation instead of the original values, but I'm getting errors.

This is the code I have tried:

topog = 100:149;
erodedSed = (0.1:0.1:5);
newTopog = topog - erodedSed;

for i = 2:10;
    newTopog(i) = newTopog(i-1) - erodedSed;
end;

But I'm getting error:

"Unable to perform assignment because the left and right sides have a different number of elements.

Error in Untitled2 (line 6)

newTopog(i) = newTopog(i-1) - erodedSed"

Basically, instead of using "topog" in every iteration following the first, I want the code to replace topog with the "newTopog" calculated in the iteration before it, and then continue doing the equation for the further steps.

Many thanks for your help!

Answer 1

[Hernia Baby]

" i " is not the number but index number(line or row).

e.g.1 using for

clear;

topog = 100:149;
erodedSed = (0.1:0.1:5);
newTopog(1,:) = topog - erodedSed;
for i = 2:10
    newTopog(i,:) = newTopog(i-1,:) - erodedSed;
end

newTopog(end,:)

e.g.2 using while instead of for (Recommended)

clear;

topog = 100:149;
erodedSed = (0.1:0.1:5);
newTopog = topog - erodedSed;
cnt = 1;
while cnt < 10
    newTopog = newTopog - erodedSed;
    cnt = cnt + 1;
end

newTopog

[Alfie Mackie]

Thank you so much! That works perfectly!

[Hernia Baby]

My pleasure!