# GeoGebra crashes when dragging the parameter to a definite integral

Hi, this applies to GeoGebra on an up-to-date Arch Linux, that is GeoGebra 5.0.290.0-3D (11 November 2016) under Java 1.8.0_121, on a fairly old HP notebook with 4 GB.

I wanted to put the calculation of the circumference of a circle in L(p) space, i.e. measured using the p-norm into GeoGebra. You have probably seen this: dividing this circumference by the diameter yields a “variable value for π”, π(p). For p=2, the norm is the Euclidian norm and takes π(p) to the standard value which is also a global minimum for the function p→π(p).

Being lazy, I used the integral formula for π(p) found at http://math.stackexchange.c... – I constructed the “p-circle” (requiring 4 loci as each locus would end considerably before its endpoint for higher values of p). Also, but not relevant to the crash, I transformed p using the function p→p/(1-p) as this way I could use [0, 1] as the input range and obtain the desired [1, ∞] interval for p with the interesting value 2 in the middle (as 0.5 maps to 2 with this transformation).

Obviously I have a slider for p that I want to drag to see how the shape of the p-circle changes. That same slider also provides the parameter for the calculation for π(p) via the definitive integral formula found on Mathematics Stack Exchange. When I drag p, GeoGebra crashes. Also, if I try to construct a Locus to draw the graph for p→π(p) GeoGebra crashes almost instantly. Actually I was able to construct the Locus and immediately save and close the file, in which case GeoGebra would crash as soon it tries to reopen the file. Luckily I know how to edit the XML definition of the construction so I could bring those files back to a usable state.

The attached file “p-circle.ggb” does open but crashes when I drag p. Some careful dragging across small values or double-clicking and entering values for p is possible. The second file “p-circle-reduced.ggb” does not crash, the difference being that it does not try to calculate or graph π(p), only show the p-circle.

Thanks for any comments.

Erratum: my transformation p→p/(1-p) maps [0, 1] to [0, ∞] of course with the middle value ½ mapping to 1, not 2. I need the source value ⅔ to get p=2.

Problems mostly occur once I pass ⅔ (corresponding to p=2) on the slider, and as p exceeds 5 my formula won’t calculate at all in GeoGebra – the output says “π(p)=?” although the integral can be computed (e.g. π(6)≈3.57).

Loading...Comments have been locked on this page!