Question

I am trying to use the return statement. If the y is negative then program will terminate. But it is showing “ValueError: math domain error”

import math
y=-5
def df(y):
if y<=0:
        print y, "is negative"
        return
result = math.log(y)
print "The log of y is",result

Answer 1

Your return is empty….there is no variable name or value on the same line with “return”. For example, if you wanted to return the value 5, you’d put

return 5

If you wanted to return a variable foo, you’d put

return foo

Right now you are returning nothing.

Maybe you want this?

import math
y=-5
def df(y):
    if y<=0:
        print y, "is negative"
        return "impossible to calculate"
    result = math.log(y)
    return result

print "The log of y is", df(y)