Equations cannot be solved in Prime version, in Mathcad 14 it still works.

[AN_10497745]

Hi all,

I need your help.

I have an old calculation, which was made in Mathcad 14. This calculation was made not by me.

This calculation perfectly works in Mathcad 14. Now we have Mathcad Prime 7 and 8.

I have converted this calculation to  *.mcdx format. And I got a problem.

The equations, which calculated using Euler method, cannot be calculated now in Prime 7 and 8 with step  5000 and more.

It show me error “ infinite recursion or overflow”.

With step 4700 it still works. Attached you can find this equations. 

Thanks in advance.

[VladimirN]

 Hi,

Can you also attach the source file for Mathcad 14?

[AN_10497745]

Hi. I can do it  only tomorrow. 

[Werner_E]

I could only test with Prime 6 and I experience no problems with a larger range tau.

I could setup tau with over 5 millions steps without any error.

So either there is a problem with your installation of Prime or once again Prime was "developed" in the wrong direction. Maybe someone with P7 or P8 can testdrive your sheet and report the results.

Here a screenshot of P6:

[LucMeekes]

Doesn't run that far in Prime 8.

I can set tau up to 4764 without error, at 4765 the expression H2(B1[tau) is flagged with an error. Prime 7 is the same.

Translated down to Prime 4 (express) and it runs easily up to tau=50000:

I think it's official. PTC broke something between Prime 6 and 7.

Success!

Luc

[Werner_E]

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I think it's official. PTC broke something between Prime 6 and 7.

I already suspected exactly that.

@AN_10497745 

You may consider reporting that bug and opening a support case if you have the least hope that it would have any positive effect.

[AN_10497745]

Hi. Thank you. Exactly the same thing. 

[AN_10497745]

Hi. Thank you for trying. I heard, that in P6 you can switch between legacy and new engine. Does it works with both of engine? Maybe you know , can I get the P6 if  I  have license  for P8?

[MartinHanak]

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@AN_10497745 wrote:

Hi. Thank you for trying. I heard, that in P6 you can switch between legacy and new engine. Does it works with both of engine? Maybe you know , can I get the P6 if  I  have license  for P8?

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Hi,

you can install P6 in case that your license file contains block of lines starting with INCREMENT MATHCAD ptc_d 26.0 .

If your license file contains block of lines starting with INCREMENT MathcadPrime ptc_d 8.0 , only >>> then you can install P7+.

[Werner_E]

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@AN_10497745 wrote:

Hi. Thank you for trying. I heard, that in P6 you can switch between legacy and new engine. Does it works with both of engine? Maybe you know , can I get the P6 if  I  have license  for P8?

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Your problem is not related to legacy vs. new  engine because your sheet doesn't use the symbolic engine at all and the change of engines only applies to the engines used for symbolic calculations.

Obviously PTCs development team has broken something in the native core functionality of Prime from version 6 to version 7. If you report this bug to PTC support, there might be a slight chance that it will be fixed in one of the future versions.

I can't test if this would be a working workaround in P7 or P8, but you may try to do the iterations not by using a range variable but rather by writing a program with a for loop which does the same.

[LucMeekes]

"do the iterations not by using a range variable but rather by writing a program with a for loop"

Tried that, with as result, the same limitation 😮. But I may have made a mistake.

Luc

[Werner_E]

Its hard to believe that they implemented unintentionally such a low limit and that it remains undetected through two versions.

13 vectors with 5001 elements each make up a total of less then 64k elements. That used to be "nothing" for Mathcad and sure should not be a limitation in Prime, too.

We'll have to see if they fix this bug in version 9. On contrary to real Mathcad PTC is quite reticent and silent when it comes to information about which bugs will be fixed in upcoming versions or are already fixed in the current one. On the other hand, they are even more creative when it comes to announcing improvements and new features that will not be realized in this form after all.

[AN_10497745]

Thank you for your help. I have written in support about this problem. 

My license file contains INCREMENT MathcadPrime ptc_d 8.0. That means I cannot use P6 version.

My license for Mathcad 14 is until the end of this  year.....I hope, support can help with this problem untill that time.