# Geogebra Crashing - Why?

Ken Ashton shared this question 2 years ago

Hello:

Try these steps:

Define the function f(x):=Normal(μ, σ, x, false)

You will have two sliders for the mean and standard deviation.

Now create the integral: Integral(f, 1, 2)

Use the slider for σ, things are ok.

Use the slider for μ: CRASH!!!

What's going on here?

I recreated the normal function pdf curve analytically (not from the built-in function) and found that the crash occurs when I incorporate the normalising factor which includes σ in the denominator.

Any comments/support would be much appreciated.

Thanks

Ken 1

PS I am using GeoGebra Classic 5.0.616.0-d (23 November 2020) 1

I have done a workaround, so the file I was creating works. Not satisfactory, but the end-user will not detect the issue.

I defined function f(x) from the analytic definition of the normal pdf rather than the built-in function.

Then I normalised it by working out the integral under the graph, from 5 s.d. below the mean to 5 s.d. above the mean (so the limits are "dynamic" and controlled by the sliders)

Then I defined function g(x) as f(x) divided by the result of the integration.

The file is intended to show students critical regions under the normal curve for significance levels set by the user.

The file allows visualisation of one- or two- tailed considerations.

Cheers

Ken 1

Thanks, great bug report :)

We'll check asap - other workarounds could be to use erf() or NIntegral() 1

Sorry, it's a bug. We'll fix it asap