Floating Point Errror

[camacogacu]

Hi everyone!

I am coding with Mathcad a worksheet that is supposed to generate the response spectra for earthquake data. I have achieved it using the Implicit Method, but when I use the Explicit Method (Central Difference Method) I get the message that there is a floating point error. Could somene please help me to fix this problem? 

Thank you

[camacogacu]

Please find attached the Mathcad file

[AlanStevens]

You have included no data for ug!!

Alan

[camacogacu]

Hi Alan!

Sorry for that, mine opens with ug inserted. Please find attached the data I used as ug.

[RichardJ]

The local variable u gets bigger with every step, and at step 97 you get a floating point overflow when calculating phat. I'll also note that udot and udotdot are not used for anything, and could be deleted.

[Werner_E]

OK, Richard has beaten me 😉

If i is 96 the multiplication a*u_i exceeds Mathcads limit of 10^307 and throws the error.

You'll have to check the algorithm used.

 For whatever it may be worth find attached the file with embedded data.

[RichardJ]

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@WernerExinger wrote:

OK, Richard has beaten me 😉

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  You were snoozing!

[VladimirN]

Or snoring ?

[Werner_E]

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@RichardJ wrote:

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@WernerExinger wrote:

OK, Richard has beaten me 😉

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  You were snoozing!

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Yeah! Looks like I am getting lazy and slow

[camacogacu]

Thank you all for your quick response! 🙂 I´ll check the algorithm used