Re: InterpolatingPolynomial error message

*To*: mathgroup at smc.vnet.net*Subject*: [mg129535] Re: InterpolatingPolynomial error message*From*: wangkang0118 at gmail.com*Date*: Mon, 21 Jan 2013 00:08:42 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <ih6ecs$3f8$1@smc.vnet.net>

> Hi Victor > > 1. The form of your data is not right for InterpolatingPolynomial (see the online documentation). > > With > > data2 = {{{105, 1.5}, 33.0127}, {{110, 1.5}, 32.2962}, {{115, 1.5}, > 31.6448}, {{120, 1.5}, 31.054}, {{125, 1.5}, > 30.5196}, {{130, 1.5}, 30.0374}, {{135, 1.5}, > 29.6036}, {{140, 1.5}, 29.2143}} > > the command would then be > > InterpolatingPolynomial[data2, {x, y}] > > to get an interpolating surface in 3D. (I am assuming that is what " i am trying to get a function" means.) > > This input however gives the message > > InterpolatingPolynomial::poised: "The interpolation points {{105,1.5},{110,1.5},{115,1.5},{120,1.5},{125,1.5},{130,1.5},{135,1.5},{140,1.5}} are not poised, so an interpolating polynomial of total degree 3 could not be found" > > If you then do > > data3 = First /@ data2 > > to get the {x,y} coordinates, and then do > > ListPlot[ data3 ] > > You'll see what is retrospectively obvious, that your original 3D points project onto a straight line on the (x,y) plane. (That's what the "not poised" message means.) How do you imagine Mathematica could construct an interpolating *surface* from this data? > > Cheers > > Barrie > > >>> On 18/01/2011 at 9:52 pm, in message <201101181052.FAA11815 at smc.vnet. net>, > VICTOR <victor.herasme at gmail.com> wrote: > > Hi, > > > > i am trying to get a function for this data set: > > > > data={{105,1.5,33.0127},{110,1.5,32.2962},{115,1.5,31.6448},{120,1.5,31.054} > > ,{125,1.5,30.5196},{130,1.5,30.0374},{135,1.5,29.6036},{140,1.5,29.2143},...} > > > > i execute the command: > > > > P=InterpolatingPolynomial[data,{x,y,z}]; And i get this error message: > > > > InterpolatingPolynomial::ipab: Abscissa specification 105 in > > {105,1.5,33.0127} is not a point in 3 dimensions. >> > > > > I dond't know what's going on. Can anyone help me please ? Regards, > > > > Victor Hi, I am trying to solve this problem by mathematica. Write a program to interpolate the function f(x,y) = cos(x) sin(y) at 16 equally-spaced points in the square (-pi,pi) x (-pi,pi), using multi-dimensional polynomials that are cubics in each coordinate. Plot the error in the function value. However, I tried a lot but still failed. I was wondering if you could help me. I sent you the attached material. Thank you so much. Kang