topic Re: Plot Issues with cosh(1/x) in Mathcad

Plot Issues with cosh(1/x)

jackclift — Thu, 03 May 2018 13:19:23 GMT

Hello,

Am trying to get a simple plot of cosh(1/x) working. It will graph the negative region (x<0) but not the positive. How do I fix that?

Regards

Jack

Re: Plot Issues with cosh(1/x)

LucMeekes — Tue, 23 Jan 2018 06:58:07 GMT

What's the problem?

Show your effort....Attach the worksheet.

(You may have to zip it first. A serious bug in this forum often prevents from attaching a mathcad file. In Windows Explorer click with the right-mouse button on the mathcad file and select 'Send to' -> 'Compressed (zipped) folder'.

The resulting .zip file can be attached.)

Success!
Luc

Re: Plot Issues with cosh(1/x)

Werner_E — Tue, 23 Jan 2018 08:14:10 GMT

You sure will have to explain what the problem is you experience and want to be fixed.

I assume you are using Prime. You have to be aware that on every axis you are able to change the first, second and last value to whatever you like (see the picture. Its rather hard to spot and to do, but, alas, plotting is something which is implemented in a ridicoulous unprofessional and insufficent way by PTC.

Re: Plot Issues with cosh(1/x)

Fred_Kohlhepp — Tue, 23 Jan 2018 11:58:21 GMT

Using Werner's tip (I didn't realize you could adjust three. . .)

I get the following:

Re: Plot Issues with cosh(1/x)

jackclift — Wed, 24 Jan 2018 00:51:13 GMT

Sorry all for the less than informative query. Attached the file that I am trying to get working, as discussed just shows the region x < 0.

Re: Plot Issues with cosh(1/x)

ValeryOchkov — Wed, 24 Jan 2018 06:53:55 GMT

With log Y scale:

Re: Plot Issues with cosh(1/x)

LucMeekes — Wed, 24 Jan 2018 12:07:09 GMT

Ah, the problem is that you don't get to see a plot for positive x.

If you define x as an appropriate range, you will:

Success!
Luc

Re: Plot Issues with cosh(1/x)

Werner_E — Wed, 24 Jan 2018 12:49:36 GMT

Ah, so you are using Mthcad 15 (or below?)! Good decision!

And from your initial post I got the impression, that you ask how you could manage to just see the plot for x<0. The opposite is the case.

And you sure found a very strange bug here. When I scale down the plot region, sometimes I see the part for x>0, sometimes not. Sometimes I see both branches when I click inside the plot region but when I click outside, the right branch won't show up.

Don't expect PTC to fix that bug.

As Luc already explained, you have more control over the plot if you don't use Mathcads quickplot feature but provide a range for x ( I usually use the variable name x. (note the dot after the x) for plotting so to keep x undefined.)

If you use a very small step width Mathcad choses a very high value for the upper ordinate. You may change the range for the ordinate by typing in more appropriate values (the circled numbers)

But now I realize, the the bug still is shown. With the step width of 0.01 the right branch of the plot still is not shown - thats crazy!

Changing the step width to a lower value (here 0.1) makes the right plot branch show up again:

So I am sorry to say that it seems that you will have to live with that bug.

Either play around with the size of the plot region until you find a good sized region which shows both branches or use a range variable with a suitable stepwidth.

Re: Plot Issues with cosh(1/x)

LucMeekes — Wed, 24 Jan 2018 14:45:46 GMT

That bug is (fortunately) not in Mathcad 11...