Index exceeds the number of array elements. Index must not exceed 1.

Pretty novice at MATLab, I'm having trouble creating a loop for my coastal engineering class. It'll run the first itieration but nothing after.

P1=load("HW2_Problem1_PeriodandH.txt");

T=P1(1:3:7,1);

H=P1(1:3,2);

for i=1:3

T=T(i)

Ko=1/(9.8*T.^2/(2*pi)^2)

end

Index exceeds the number of array elements. Index must not exceed 1.

Error in HW2 (line 11)

T=T(i)

Answer 1

[Voss]

This line:

T=T(i)

takes the ith element of T and stores it as T, after which T is a variable with one element. So any subsequent attempt to access T(i) when i > 1 will fail because T has only one element.

Instead, use another variable (i.e., don't overwrite T):

for i=1:3
    Ti=T(i)
    Ko=1/(9.8*Ti.^2/(2*pi)^2)
end

Or better, just use T(i) when you need it (no need for another variable at all):

for i=1:3
    Ko=1/(9.8*T(i).^2/(2*pi)^2)
end

[Andrew Mosqueda]

Thank you. I used the latter code and it runs, however, I'd like to save my Ko answers in a matrix for later use and it only saves the 3rd itieration. How would I go about this?

[Voss]

Make Ko a vector and calculate one element of it on each iteration of the loop:

for i=1:3
    Ko(i)=1/(9.8*T(i).^2/(2*pi)^2)
end

Of course, if that's all it does, the for loop is not needed at all:

Ko = 1./(9.8*T.^2/(2*pi)^2);