Re: machine precision number plot fixed in V6?

*To*: mathgroup at smc.vnet.net*Subject*: [mg83062] Re: [mg83043] machine precision number plot fixed in V6?*From*: Brett Champion <brettc at wolfram.com>*Date*: Fri, 9 Nov 2007 05:13:49 -0500 (EST)*References*: <200711081113.GAA27782@smc.vnet.net>

On Nov 8, 2007, at 5:13 AM , congruentialuminaire at yahoo.com wrote: > Hello Mathematica UG: > > I was doing some work with the PrecisionPlot package (http:// > library.wolfram.com/infocenter/MathSource/715/) > > When I ran it under V6, no output was emitted. So I looked again at > the documentation provided by Ted Ersek. Even though it is 8 years > old, it contains the following function and plot which does not work > correctly as recently as V5. > > In V6, the invocation with SetPrecision works and emits a smooth plot > (presumably eliminating the need for this package). Here are the lines > of code. > > ----------------------------------------------------------- > (* a function that does not plot well with machine-precision numbers > *) > f2[x_] = ArcSec[x] - Normal[Series[TrigToExp[ArcSec[x]], {x, \ > [Infinity], 7}]] > > (* a jagged plot results under V5 and V6 *) > Plot[f2[t], {t, 25, 40}] > > (* a smooth plot results only under V6 *) > Plot[f2[SetPrecision[t, 17]], {t, 25, 40}] > ------------------------------------------------------------ > > If there is a simple explanation for what was fixed in V6 to make this > work, I am interested to know. In V6 Plot can take a WorkingPrecision option, so this will also give a smooth curve: Plot[f2[t], {t, 25, 40}, WorkingPrecision -> 17] Brett Champion Wolfram Research

**References**:**machine precision number plot fixed in V6?***From:*congruentialuminaire@yahoo.com