For Loop Iteration With Part of Vector

I want to use a row vector to index in a for loop. But, I want to switch to a different function when the index reaches a certain element in the vector. My row vector (t) is 1x1271810. I would like to use my first function in a for loop up to element 945665 in the vector, and then use a different function for the rest of the for loop (or another for loop) from element 945666 to 1271810. Is this possible? Here is how I have my for loop written so far, how would I modify it?:

[a,b] = size(t);
for i = 1:a
  for j = 1:b 
    PredCurrFun(i,j) = p(4).*((1-calcPinf(p,t(i,j),Co(i),Diff)).* ...
        exp(-calcLambda(p,t(i,j),Co(i),Diff) .* t(i,j)) + calcPinf(p,t(i,j),Co(i),Diff)); 
  end
end
"second function I would like to use is a 1 - exponential"

Answer 1

[Charles DeLorenzo]

I would suggest using one for loop the length of 't' and a conditional statement to switch between the functions. As an example

for i=1:width(t)
    if i<945665
        % function 1
    else
        % function 2 
    end 
end

[Kelly McGuire]

Hey Charles, thanks for the response! I get the error: Index exceeds array bounds. Here is my new code:

for i = 1:length(t)
    if i < 945665       
            PredCurrFun(i) = p(4) .* ((1 - calcPinf(p,t(i),Co(i),Diff)) .* exp(-calcLambda(p,t(i),Co(i),Diff) .* t(i)) + calcPinf(p,t(i),Co(i),Diff));          
      else      
            PredCurrFun(i) = exp(-calcLambda(p,t(i),Co(i),Diff) .* t(i));  
    end
end
end

[Kelly McGuire]

The error is gone with this code, but I'm not sure if the second function is actually being used:

[a,b] = size(t);


for i = 1:a
    for j = 1:b
    if j <= 945665       
            PredCurrFun(i,j) = p(4) .* ((1 - calcPinf(p,t(i,j),Co(i),Diff)) .* exp(-calcLambda(p,t(i,j),Co(i),Diff) .* t(i,j)) + calcPinf(p,t(i,j),Co(i),Diff));          
      else      
            PredCurrFun(i,j) = exp(-calcLambda(p,t(i,j),Co(i),Diff) .* t(i,j));  
    end
    end
end
end

[Charles DeLorenzo]

I'm glad I was able to get you a little further along.

I see why my first answer was confusing, since I did not include both dimensions of the array 't'. You did good by nesting the two for loops on i and j. My answer should have been

[a,b]=size(t)
for i=1:a
    for j=1:b
        if j<945665
            % function 1
        else
            % function 2 
        end 
    end
end

as you already have.

It's hard for me to troubleshoot your code segment above without being able to run it, so I cannot provide a definitive answer on why the second function isn't being used. I would suggest using a conditional breakpoint to stop the if statement when j=945665 to see what's going on. Then, you can manually step the code to see if the second function is being calculated. Conditional breakpoints are under the 'Editor'-->'Breakpoints'-->'Set Breakpoint'. The 'Debug' menu will appear under 'Editor' after the code runs with the breakpoint.

[Kelly McGuire]

Great, thanks for the advice! That was very helpful.