# Locus doesn't appear for some parameter values

llgalante12 shared this question 2 months ago

Hello,

I have a problem in visualizing the locus defined by two points:

1. the first is a point E constrained on a segment on the (x,y) plane,
2. the second is the a point U which is the head of an oscillating vector (whose tail is E) directed along the z-direction.

The locus is a time dependent sinusoid. In order to give the opportunity to see the locus propagating along the segment as time passes I have added a button to increment t each time you press it. It works, however for some values of t the locus does not appear.

(this a link to my app: https://www.geogebra.org/m/defnkdqf)

1

Which values of t? Please can you post a screenshot?

1

In this image you see the two vectors (in E and F) and the points on the head of each one, whose loci I want to show.

Here the loci for t = 0:

Here the loci for t = 0.1 (the orange locus doesn't appear):

here the loci for t = 0.2 (both loci appear):

Both the blue and orange loci, for some values of t, are not shown. The value of t depends on the position of the point P (green) on the SCREEN line.

Best regards,

Lorenzo

1

Here's what I have for t=0.1. Can you try on some different computers?

1

OK, so the green point needs moving as well as the slider?

https://www.geogebra.org/m/ajmh9zvq

1

Does this work better? If not then you could try using Curve() which will be more robust

1

Dear Michael, I've followed your advice ... I've used the Curve() command which turns out to be a lot more stable! The problem seems to be solved. Thank you so much! Lorenzo