I tried to execute this simple command

Plot[Cosh[t] - Sinh[t] + Sin[t], {t, 0, 40}]

and this is the result I got

enter image description here

As you can see, there is an unexpected visual between $t=30$ and $t=40$. But when I used the identity $e^{-t}=\cosh{t}-\sinh{t}$, everything went fine. This command

Plot[Exp[-t] + Sin[t], {t, 0, 40}]


enter image description here

What's going on here? Can anyone reproduce this result? Is this a bug? I'm using MMA 12 64bit on Windows 10.

  • $\begingroup$ Try the MaxRecursion option for Plot. It is generally used to control adaptive sampling. $\endgroup$ – Lotus Feb 9 '20 at 10:30
  • 4
    $\begingroup$ Both $\cosh x$ and $\sinh x$ functions are diverging at large positive $x$ as $e^x$. For these values are hard to achieve perfect cancellation between the two functions. $e^{-x}$ does not have this problem. Use WorkingPrecision -> 30 option of Plot to get the same result. $\endgroup$ – yarchik Feb 9 '20 at 10:57
  • $\begingroup$ Plot[Cosh[t] - Sinh[t] + Sin[t], {t, 0, 40}, PlotPoints -> 4] this can partly solve it. $\endgroup$ – wuyudi Feb 9 '20 at 15:35
  • $\begingroup$ The same happens for me (v11 on Windows 10), WorkingPrecision -> 20 corrects it. $\endgroup$ – მამუკა ჯიბლაძე Feb 10 '20 at 7:25

I think there is a problem with your main file. I tried your command and the result is ok. My Mma version is 12.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.