Undefined variable for plotting if statement array

I have a script where I'm taking values from an array and plotting the values that satisfy an if condition. But for some reason it claims that one of the variables is undefined even though I defined it under the if statement. When I look at the error message at the line, it says that the variable xplot appears to change size after every iteration. How do I resolve this?

Answer 1

[Walter Roberson]

If lowDistidx never becomes true, then you might never assign anything into xplot or yplot.

We cannot tell from what you posted whether possibly hdiff is a vector -- in which case the condition might be true for some of its members but false for other of its members.