topic Re: PLOT ERROR in Mathcad

PLOT ERROR

ssato — Thu, 03 May 2018 13:12:32 GMT

I have a quetion.

I attatched the file.

I do not understand the error on last plot of file.

I think "n" is no problem.

Best Rgs

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 08:39:57 GMT

I do not understand the error on last plot of file.

I think "n" is no problem.

I agree and as I don't see any rational reason for this error I would call it a strange Prime bug.

Prime seems not to like the fact, that only every fourth value is non-zero? Not sure what exactly causes that bug.

But I can confirm that it should work and it also does work OK in Mathcad 15

I found two possible workarounds to do it in Prime (not satisfactory but at least you get your plots):

1) change the factor 2 of the cosine to something close to 2

2) change the step width of your range n to 1,1.5 .. 50

Re: PLOT ERROR

Fred_Kohlhepp — Wed, 25 Apr 2018 11:55:03 GMT

Interesting! In Prime 3.0:

Going backwards?

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 12:12:56 GMT

Fred, your function v differs from the original function. The 2 is only a factor of the cosine.

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 12:32:48 GMT

Here is another workaround using a different, but equivalent function:

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 12:50:41 GMT

Here are two other workarounds using the round function

I also noticed, that if we change the range from n:=1,2...50 to n:=1,2...7 Prime has no problem. But as soon as we go up to 8 or more - error. Thats crazy.

Re: PLOT ERROR

Fred_Kohlhepp — Wed, 25 Apr 2018 14:48:14 GMT

Sorry, needed more coffee!

Still:

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 15:02:43 GMT

Yeah! Lack of coffee really can have bad side effects 😉

But nonetheless we see that your Prime 3.0 plot is quite happy with that expression.

So the bug seems to be newly introduced in Prime 4.0 (guess it works still OK in P31, too).

Maybe the only left-over of the plot enhancements we were promised that Prime 4 will include.

Re: PLOT ERROR

DJF — Wed, 25 Apr 2018 15:10:36 GMT

Don't we just need n to be a vector (not a range)(add the = sign) and vectorize the equation?

Re: PLOT ERROR

Fred_Kohlhepp — Wed, 25 Apr 2018 16:31:48 GMT

There are two primary uses for range variables:

As indices for vectors, and
As plotting independent variables.

If making n a vector fixes this problem in Prime 4, then it's still a bug, and an aggravating one.

Re: PLOT ERROR

Werner_E — Wed, 25 Apr 2018 17:38:46 GMT

Sure, this is a valid workaround, too. Given that we don't need n as range later.
Point for me is that it should work as initially done and due to a, obviously freshly (as Fred showed) introduced, bug it doesn't.

I might add a third use to Freds list - ranges are also needed in programs for for-loops.

Re: PLOT ERROR

ssato — Wed, 25 Apr 2018 23:43:57 GMT

Thank you. everyone.

I will attach another file.
If "a" is an odd number in the last graph, an error will occur only with graph creation.
If "a" is an even number, no error occurs.

In the end, is this a bug in Prim 4.0?

If you are a bug, where should I contact?

Re: PLOT ERROR

Werner_E — Thu, 26 Apr 2018 10:17:06 GMT

It sure IS a bug and obviously a new one as Fred head shown that in Prime 3.0 it works OK

PTC is not very interested in bug reports.

In fact you have to pay for the privilege(!) to send a bug report - only if you are under maintenance you may open a support ticket an report that bug.

Re: PLOT ERROR

LucMeekes — Thu, 26 Apr 2018 12:03:10 GMT

And then it may take a while to get fixed...

Success!
Luc

Re: PLOT ERROR

Fred_Kohlhepp — Thu, 26 Apr 2018 12:27:24 GMT

@LucMeekes wrote:

And then it may take a while to get fixed...

My stopwatch doesn't carry intervals long enough!

Anybody have a "stop calendar"? 😉

Re: PLOT ERROR

LucMeekes — Thu, 26 Apr 2018 12:41:55 GMT

As a matter of fact, I have a small clock that I can set for a (one) date and time in the future. If it reaches that point in time it will sound the alarm; it was initially set for 2000-01-01 00:00 and would show how many days until the set time. I don't have one that counts up, but they're not too difficult to make on a web site.

Come to think of it:

Would be fun to have a down counter to the predicted date of https://community.ptc.com/t5/PTC-Mathcad-Questions/Mathcad-Prime-5-0-some-new-updates/m-p/489877#M174257 as a reply to that post.

Luc

Re: PLOT ERROR

Werner_E — Thu, 26 Apr 2018 16:34:50 GMT

@Fred_Kohlhepp wrote:

@LucMeekes wrote:

And then it may take a while to get fixed...

My stopwatch doesn't carry intervals long enough!

Anybody have a "stop calendar"? 😉

How's a calendar called which covers more than just one year?

Re: PLOT ERROR

ssato — Thu, 26 Apr 2018 23:04:08 GMT

Everyone, I understood well.......