Function arc length on 50G  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: Function arc length on 50G (/thread140178.html) 
Function arc length on 50G  Hal Bitton in Boise  08252008 Hi folks, Re: Function arc length on 50G  George Bailey (Bedford Falls)  08252008
I don't think there is a dedicated function available. But with the formula from the above article, you might want to write a tiny program of your own... (I suspect you know that formula already) Edited: 25 Aug 2008, 12:42 p.m.
Re: Function arc length on 50G  Hal Bitton in Boise  08252008 Thanks George, Re: Function arc length on 50G  Marcus von Cube, Germany  08262008 The 50g makes it easy to define the function yourself:
'AL(a,b,f,x)=Integral(a,b,SQRT(1+SQ(DERIV(f,x))),x)'Substitute the words in italics by their respective symbols. This defines the variable AL as a short program with just an arithmetic expression (the right hand side of the above equation) as its body. The function takes parameters similar to the built in symbolic integration. You'll have to force numeric evaluation (>NUM) if you want to see numeric results.
If anybody detects a typo, please correct me.
Re: Function arc length on 50G  George Bailey (Bedford Falls)  08262008 Marcus, thanks, it works great, no typo!
Just don't forget to purge x before executing AL, in case you have stored a value in it..: ;) Or else you'll get an error!
Re: Function arc length on 50G  Marcus von Cube, Germany  08262008 If you use lower case variable names the danger of having accidently stored anything there is low.
The program creates four local variables: a, b, f and x. I was hoping that x in the expression is treated as a local formal variable. I'm not sure if that works. If the local variable x holds the name of the variable passed as the 4th argument to AL, this name matters. If you pass X and X exists and holds a value you might get into trouble.
