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(50g, 49g) ArcLength v1.1 - The lenght of arch of given function
06-05-2018, 07:51 PM (This post was last modified: 06-06-2018 05:26 PM by Vtile.)
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(50g, 49g) ArcLength v1.1 - The lenght of arch of given function

I were faced on the problem at work today where I need to solve the length of arc and to be honest the algebraic solution had buried so deep dust in my head that it didn't ring any bells. So next step open 50g AUR and look a function Smile No there is none unfortunately. So next best thing were a net search with 50g solution:

Unfortunately the solution given on that oldish MoHPC thread doesn't work for some reason on my 50g, the derivative inside integral somehow generates a bug. In RPL stack it does work, but not as a defined algebraic function so I did create a code snippet for it.

Length of arch of given function:
IFERR // Works as documentation mainly
RAD  // Radians mode - Just to be sure it does give a right solutions
'DERIV(f,x)'  // Could be implemented as RPN
EVAL // This is here because of algebraic expression above
INTEGRAL  // Symbol
THEN // These 4 objects are mainly as a description of use
" Give RANGE, f(x), x (a,b,f,x)
The speed and accuracy is disp.
format dependent."

I have tested this against wolfram alpha and so far it does give approx. right values, but only in 1 decimal accuracy depends on the display settings/mode/format. Another option is that Wolfram Alpha does calculate incorrectly as it gives "Standard computational time exceeded..." message. I also did misuse the Parisses XCAS and copypasted the derivative of the f(x)=2x*Sin(10*x) from WA to XCAS and used integral there from 1 to 2 and the values between XCAS and WA do agree, while 50g with above program do not after the first digit. Any ideas? EDIT1: Above program also generates at times IERR variable "Integral ERROR" maybe, unfortunately at this time of night I can not recall.

Hopefully this is useful to somebody, but read the above notes about accuracy (see posts #2 and #3).

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(50g, 49g) ArcLength v1.1 - The lenght of arch of given function - Vtile - 06-05-2018 07:51 PM

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