Scratch

I created a program that simulates using the quadratic formula. The program outputs the roots of a quadratic equation given 3 inputs, a, b, and c, which are set up as variables.

I teach high school math, so I'm demonstrating to the students how scratch can be used in fun ways, to supplement what we're already doing in the classroom.

(Anyways, for those who need a brief refresher, some quadratic equations have
complex roots, where the discriminant in less than zero. In other words, the graph does not cross the x-axis in the real number plane. In other words, there are imaginary roots, with the number "i", the square root of negative one.)

It appears to me that the math functions built into scratch do not allow for
complex roots or "i" as a number. Therefore, I have sort of an error check built into the
user interface, where, if a,b, and c, produce a parabola which has complex roots, then the character on the screen, says something like this: "Sorry, you're quadratic equation does not cross the x-axis. Scratch doesn't do imaginary roots. Hit the green arrow to start over with a problem that has real roots."

So, when I view the program from the scratch application interface, to test the program,
this error-checking message works fine.
I uploaded the program to the Scratch website. On the Scratch website, on a web browser, this message does not appear when there are imaginary roots.
The message the appears is "The roots are NaN, and NaN..."
This clearly indicates to me that the program is interpreting complex roots and
giving them the value 'NaN' which is some type of error checking variable within
the Scratch API.

Can someone tell me what to do to make the program work on the website
in the exact same way it works from the Scratch application on my desktop.
This is the program:

http://scratch.mit.edu/projects/mandostop1/2374673

Thank you very much.

Tim May
(mandostop1)