odd result when plotting offset circle

[relayman357]

This isn't urgent, I'm just curious here, but in the attached Prime 8.0 file I'm plotting an offset circle in steps from 0° to 360°.  When I reduce the resolution by going to 10° steps I get the interesting figure on the right.  Why is that happening?  

[Werner_E · Accepted solution]

1) In your sheet you set line style to "none" so we possibly won't see what your picture shows.

2) You don't show HOW you would manage a step width of 10°. If you do it correctly, you will see exactly what you expect.
Here with Line Style set to full line:

I guess you just used

which would explain what you posted.

That way there still is created a vector with 361 elements!!

But only elements #0,10,20,... get the values you intend, the rest is filled with zeros by default.

You may consider using something like

or

A less "legal" but convenient way uses the undocumented (and so unreliable) trick that an inline evaluation turns a range into a vector

Don't try to set the unit deg at the result - it will throw an error.

[relayman357]

Thank you Werner!

1) Yes, sorry - I forgot to mention I changed i:=0,1..360 to i:=0,10..360 to go to 10 degree steps.

2) I didn't know i:0,10..N still produced N+1 elements. I thought it would produce N/10.

That undocumented trick is very interesting.  

Thank you for getting me back on track!

[Werner_E]

---

2) I didn't know i:0,10..N still produced N+1 elements. I thought it would produce N/10.

---

The range "values" (actually a range is kind of an implicit loop) are used to address the vector elements.

If the range ist defined as i:=0,10..N and you assign v[i := ..., then you assign values to vector element #0, #10, #20, .... and the elements with other numbers like #3 oder #12 are left undefined and so Prime sets them to zero. You can't expect that with i=10 Prime assign the value to vector element #1.

When you write v[20:=123 you create a vector with 21 elements. element #20 holds the value 123 and the elements from #0 to #19 are set to 0.