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giordandue
Italy
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 Posted - 11/04/2026 : 08:07:35 AM
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OriginPro 2026b (64-bit) SR2
Operating System: Windows 11 enterprise
Good morning,
I have modelled one equation for nonliner curve fitting (basic reference Jaeger and Cook formulation, 1969),including the conditioning function "if", as well as some command as ">=". When I run Quick Check, I get the correct result (see the attached figure, controlled also by Excel). Nevertheless, by proceeding the input process by "Next" bottom and entering the parameter ranges, etc, one error in fitting occur ("it did not converge - mutual dependency exists between parameters"). What is strange is that by repeating the input process, I observe that the entered equation is immediately changed in the first successive step to the "Quick Check": the term "if(" is substituded by "0," and the equation part related to the ">=" disappeared. Of course, the modified equation does not allow to get a regular result by Quick Check. On the contrary, by adjusting the equation, again I get the correct result. Finally, I remark that input parameters are only shear strength properties. As a last attempt, I removed also the stress parameter s3 by entering its specific value of zero, as you can see in the attached screenshot. Thank you very much for your opinion.  |
Edited by - giordandue on 11/04/2026 09:45:42 AM |
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snowli
USA
1495 Posts |
Posted - 11/04/2026 : 08:50:02 AM
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Hello,
Could you submit ticket to our tech support
https://www.originlab.com/newticket
Please attach the defined fitting function file (fdf) and opju file with data so we can try it. You can zip them to attach.
It's hard to check it with the screenshot. E.g. there is no ">=", "s3" in image below.
Thanks, Snow |
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giordandue
Italy
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Posted - 11/04/2026 : 09:02:42 AM
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I attach also the OriginLab file. As remarked in the previous message, please, let you observe that the original equation results modified. The latter is called JaegerCook69 in User Defined equations.
The original equation stands as in the following (the values zero has been just directly input as specific value of the stress s3, as another useless attemps of solve the problem by reducing the number of parameters:
s1=IF(MIN(0+2*(ct+0*TAN(RADIANS(ft)))/((1-TAN(RADIANS(ft))*TAN(RADIANS(BETA)))*SIN(RADIANS(2*BETA))),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0))>=0,MIN(0+2*(ct+0*TAN(RADIANS(ft)))/((1-TAN(RADIANS(ft))*TAN(RADIANS(BETA)))*SIN(RADIANS(2*BETA))),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0)),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0))
If this equation is input, the correct result is achieved: s1=94.6MPa
https://my.originlab.com/ftp/forum_and_kbase/Images/giordandue1_example.zip |
Edited by - giordandue on 11/04/2026 10:20:11 AM |
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giordandue
Italy
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Posted - 11/04/2026 : 09:25:25 AM
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Hello Snowli
thank you for your reply. I should have opened a new ticked as required and in my second message I attached as well the Origin Lab file for your check.
Please, let me know, if all is ok.. |
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YimingChen
1702 Posts |
Posted - 11/04/2026 : 10:21:04 AM
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Could you change to LabTalk Script as the function type and try again?
Thanks
Yiming
quote:
Originally posted by giordandue
I attach also the OriginLab file. As remarked in the previous message, please, let you observe that the original equation results modified. The latter is called JaegerCook69 in User Defined equations.
The original equation stands as in the following (the values zero has been just input in place of the stress s3, as another useless attemps of solve the problem by reducing the number of parameters:
s1=IF(MIN(0+2*(ct+0*TAN(RADIANS(ft)))/((1-TAN(RADIANS(ft))*TAN(RADIANS(BETA)))*SIN(RADIANS(2*BETA))),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0))>=0,MIN(0+2*(ct+0*TAN(RADIANS(ft)))/((1-TAN(RADIANS(ft))*TAN(RADIANS(BETA)))*SIN(RADIANS(2*BETA))),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0)),(2*cm*(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))^0.5+(1+SIN(RADIANS(fm)))/(1-SIN(RADIANS(fm)))*0))
If this equation is input, the correct result is achieved: s1=94.6MPa
https://my.originlab.com/ftp/forum_and_kbase/Images/giordandue1_example.zip
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giordandue
Italy
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Posted - 11/04/2026 : 10:47:49 AM
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Thank's for help, Yiming: I observe that consequently to your suggestion, Quick Check gives now only the message: s1 = 0 (Variable(s) "s1" not used), without showing the correct result than before. On the other side it seems that the overall final result remain similar than before, again showing previous error messages. |
Edited by - giordandue on 11/04/2026 11:25:46 AM |
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YimingChen
1702 Posts |
Posted - 11/04/2026 : 11:26:57 AM
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Make sure to put the entire equation
Yiming |
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giordandue
Italy
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Posted - 11/04/2026 : 11:48:39 AM
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Very good, Yiming: now it seems that it works well.. I still have some minor difference with excel, but of course I have to check what is the more correct result (and maybe to understand why it is necessary to use LabTalk script..)
In the meantime, thank you very much for your suggestion!! |
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Problem with fitting function builder