How do I get rid of "This variable is undefined"?

[eyang]

I'm using a while loop to evaluate a function. Then variables of the function is output for graphing purposes. However, I get an error message of "This variable is undefined"? How do I get rid of this message?

Thank you-

[AlanStevens · Accepted solution]

1. Use vi not v in the while test. (Set initial value for i)

2. Don't reassign v to vi at the end of the while loop.

See attached.

Alan