Two bugs in recent versions

[Daniel Schroeder]

A student of mine has an older computer that can't seem to run Web VPython 3.2, so he uses 3.1 instead. No problem, I thought, until he discovered two bugs:

1.  The expression "-1**2" generates an error in versions 3.0 and 3.1.  The expression "-(1)**2", with parentheses around the 1, does not generate an error, but incorrectly evaluates to +1 in versions 2.9, 3.0, and 3.1. See example program here: https://glowscript.org/#/user/dschroeder/folder/Public/program/mathIssue/edit

2.  When you set the data attribute of a gcurve to a list with more than about 100 ordered pairs, some of the list elements can get dropped. This issue seems to occur in versions 2.7 through 3.1, but not in 2.6 or 3.2.  Exactly when elements get dropped seems to depend on the data. See example program here: https://glowscript.org/#/user/dschroeder/folder/Public/program/gcurveDataIssue/edit

Any insight into what's going on here?

Relatedly, is there an easy way to see what has changed with each new version of Web VPython?

Dan

[Steve Spicklemire]

Hi Daniel,

> On Feb 22, 2025, at 4:02 AM, 'Daniel Schroeder' via Glowscript Users <glowscri...@googlegroups.com> wrote:
>
> Any insight into what's going on here?

I believe the -1**2 is something Bruce fixed in 3.2, here:

https://github.com/vpython/glowscript/commit/fc4ab038528661e31eb338ccfc22152ea4c549f5#diff-c5e06395fc07406665368f378fd4aa946cee660714d79d39d85586c67e59a27fR366

I have no idea how difficult it might be to address the same issue in earlier versions of glowscript, but I can look into it.

I have no idea about the gcurve issue either! But I can look into that as well.

>
> Relatedly, is there an easy way to see what has changed with each new version of Web VPython?
>

Every change in glowscript since Dec 2014 is available in the commit history on GitHub here:

https://github.com/vpython/glowscript

3.1 -> 3.2 appears to have happened around Oct 2021, so it’s been a while!

[Daniel Schroeder]

Hi Steve,

Thanks very much for the quick reply.

Sadly I'm not smart enough to get anything out of what I'm seeing at either of those GitHub links.

Besides the hardware incompatibility that this particular student encountered, my students and I sometimes use older versions because they give better performance.

Dan

> On Feb 22, 2025, at 2:57 AM, Steve Spicklemire <stevespi...@gmail.com> wrote:
>
> Hi Daniel,
>
>> On Feb 22, 2025, at 4:02 AM, 'Daniel Schroeder' via Glowscript Users <glowscri...@googlegroups.com> wrote:
>>
>> Any insight into what's going on here?
>
> I believe the -1**2 is something Bruce fixed in 3.2, here:
>

> https://www.google.com/url?q=https://github.com/vpython/glowscript/commit/fc4ab038528661e31eb338ccfc22152ea4c549f5%23diff-c5e06395fc07406665368f378fd4aa946cee660714d79d39d85586c67e59a27fR366&source=gmail-imap&ust=1740823079000000&usg=AOvVaw1AQ1EhmN0dMpHUF9Nq_1iY

>
> I have no idea how difficult it might be to address the same issue in earlier versions of glowscript, but I can look into it.
>
> I have no idea about the gcurve issue either! But I can look into that as well.
>
>>
>> Relatedly, is there an easy way to see what has changed with each new version of Web VPython?
>>
>
> Every change in glowscript since Dec 2014 is available in the commit history on GitHub here:
>

> https://www.google.com/url?q=https://github.com/vpython/glowscript&source=gmail-imap&ust=1740823079000000&usg=AOvVaw2MYbJy_KD077DFWtBRC_9J

>
> 3.1 -> 3.2 appears to have happened around Oct 2021, so it’s been a while!
>
>

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[Bruce Sherwood]

See http://localhost:8080/docs/VPythonDocs/rate.html#animation-speed:

Animation Speed

Web VPython is intrinsically faster than Python, because it is transpiled to JavaScript, and JavaScript loops are significantly faster than Python loops. However, the addition of Python dictionaries to Web VPython in version 3.2 has led to a slowdown of some Web VPython loops. In most situations this will not be noticeable. However, if your code is loop intensive (for example, if you are animating a large number of particles at once), you may wish to disable dictionaries by changing the first line of your program to:

Web VPython 3.2 nodictionary