Attempted to access X(1). Unable to acces because numel(X)=0

Hi,

I am trying to write a code that selects a portion of an array read from a .csv file by promptimg the user to input the first entry and last entry. But I get the error:

"Attempted to access X(1). Unable to acces because numel(X)=0"

And the full array is not formed. This is a portion of the code:

            Y=xlsread('Book1.xlsx', 'a1:a500')

             prompt = ' What is first? ';
            f1 = input(prompt);
            prompt= 'What is last number? ';
            f2 = input(prompt);

           y=[(Y(f1)):Y(f2))]

any ideas?

Answer 1

[Image Analyst]

You do not have an array X in that code, so how could you have gotten that error message? Please GIVE ALL THE RED TEXT . Don't snip or paraphrase like you did. We want it all : line numbers, traceback, code statements, everything .

[anna]

So this is my test code and it is giving the same error:

C = xlsread('H:\Book1.xlsx','a1:ak200');

            x1=(C(:,4));

             prompt = 'What is first number? ';
            f1 = input(prompt);
            prompt= 'What is last number? ';
            f2 = input(prompt);

            X1=[x1(f1):x1(f2)]

           y=interp1(X1,[1:18]);

This is the error I'm getting: X1 =

   Empty matrix: 1-by-0

Attempted to access X(1); index out of bounds because numel(X)=0.

Error in interp1 (line 160) extptids = Xq < X(1) | Xq > X(end);

Error in test (line 16) y=interp1(X1,[1:18]);

Why is X1 coming out an empty matrix?

[Image Analyst]

anna's "Answer" moved here:

the reason I'm paraphrasing is b/c I do not have matlab access nor access to the file at the moment so this is what I know from memory. However, I do not have a "X" array at all in my file. But the error does indicate an "X". The array it is not forming is the "y" array. Everything before that is fine.

[Image Analyst]

This does not make much sense:

X1=[x1(f1):x1(f2)]

What if f1=4 and f2=30 and x1(4) = 123.456, and x1(30) = 43.2? What do you want X1 to be?

Maybe you want X1 to be the subarray from element f1 to element f2. In that case you'd do

X1 = x1(f1:f2);