How do I input two different vectors, r and h, into an equation?

So I'm creating a function for C, that needs to input the first element of vector r, and the first element of vector h, and calculate the cost. I chose to create a for loop, and the first part works fine for calculating h. Once I obtain h, I use that in an equation for C that is a function of both r and h. **r is supposed to be from 2:10. ** h kept beginning with 0, so I changed my code to r+1, with r being from 1:9 to get my correct vector for h.

After this first code runs, r changes to 10. When I run my 2nd code, again r changes to 10, and my loop runs the following (r,h) values: (10, 46.xx), (10, 19.xx), etc. when it should be: (2, 46.xx), (3, 19.xx), etc. Essentially my radius should iterate 2,3,4...10 but it automatically changes to 10. How do I get it to iterate elements of both r and h?

h = 0;
for r= 1:9

        h(r) = (600 - (2*pi*(r+1)*(r+1)*(r+1)/3))/(pi*(r+1)*(r+1));
end
display(h);

----------------------------------------------------------------------
C = 0;
for r= 1:9 h= h
   
    C = 300*2*pi*(r+1)*(h) + 400*pi*(r+1)*(r+1);
   
end

Answer 1

[Raj]

I am not sure where is the issue.I have just tweaked the second half of your code a little bit. The second loop uses values of (r,h) as (2, 46.xx), (3, 19.xx), etc. and computes value of C accordingly for each combination:

C = 0;
for r= 1:9 
    %h= h
    C = 300*2*pi*(r+1)*h(1,r) + 400*pi*(r+1)*(r+1)
   
end

So things look fine to me.

[Billy Worley]

Running this just give me one C value result, instead of the 9 it should be displaying.

Follow up question: Can you do linspace inside a for loop? Normally it iterates by 1,2,3,4, can you make it iterate by 0.5's for example? Or do you need to take another route?

[Raj]

1) "Running this just give me one C value result"- The code is doing what it is supposed to do. C value gets updated for every run of the loop and in the end you get only one value which is the last value. If you want to store all the 9 values then use this (same as what you have used in your first loop):

C = 0;
for r= 1:9 
    %h= h
    C(r) = 300*2*pi*(r+1)*h(1,r) + 400*pi*(r+1)*(r+1)
 end
display(C);

2) You can change increment value of 'for' loop like this

for r=1:0.5:10 % r starts at 1 and increments in steps of 0.5 till 10