When multipling two different "Triangle Waveform.vi"s

[dream4me]

When I multiply two "Triangle waveform.vi" with different amplitudes and frequencies,

the result is not linear but non-linear such as attached picture.

Is it a bug?

or 

Am I making a mathematical mistake?

    

[santo_13 · Accepted solution]

Looks fine to me, why would you think it is a mistake or bug? try doing the same on a piece of paper.

[Kevin_Price · Accepted solution]

[Edit: oops, queued it up, walked away, and finished later.  Kinda redundant now.  Oh well, here it is anyway...]

Well....

y1 = a*x

y2 = b*x

so y1*y2 = a*b*(x^2)

...which explains the parabola shapes in your graph.  A linear shape would result from *adding* the two waveforms.

-Kevin P

[dream4me · Accepted solution]

As you said, I wrote it down on a piece of paper and then I had known the reason about that.

Thanks a lot.

[Bob_Schor]

Oops, I didn't see that this had already results in responses and a "solution" ...  

You aren't making a mathematical "mistake", but do have a mathematical "misunderstanding".  Suppose I have a function f(x) = x, and I multiply this function by itself and call the result g(x).

g(x) = f(x) * f(x) = x * x = x².

You are multiplying two linear functions and are seeing piece-wise quadratic results, what you should have expected.

Bob Schor