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From:  P <prashanthramu@gmail.com>
Newsgroups: comp.soft-sys.matlab
Subject: Re: syms and vpa problem
Date: Wed, 08 Aug 2007 04:43:26 -0000
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On Aug 7, 9:48 pm, "Steven Lord" <slord@mathworks.com> wrote:
> "P" <prashanthramu@gmail.com> wrote in message
>
> news:1186516859.503046.118710@22g2000hsm.googlegroups.com...
>
>
>
> > Hi all,
>
> > I have a variable called
>
> > sym_dPhi =
> > -282270057375923/2361183241434822606848*cos(phis
> > +2835403426559781/1125899906842624)-5849622991223293/18889465931478580854784*cos(phis
> > +1649123417284613/281474976710656)+8867307977828847/75557863725914323419136*cos(phis
> > +1667188769632673/281474976710656)-6776253911855553/18889465931478580854784*cos(phis
> > +5867111522062989/9007199254740992)+7154406299740559/75557863725914323419136*cos(phis
> > +6355945788037667/1125899906842624)
>
> > where phis is created as syms phis.
>
> > vpa(sym_dyPhi,5) yields me
> > ans =
>
> > [ empty sym ]
>
> > Why ?
>
> Do you have a typo in your command or in your posting?  In the first output,
> your variable is named sym_dPhi, while in your command it's sym_dyPhi.  If
> you had a variable named sym_dyPhi that was empty, VPA would return an empty
> sym.  Alternately, if the line in this posting has a typo and you're
> actually computing vpa(sy_dPhi, 5), what is phis at the time you call VPA?
>
> --
> Steve Lord
> slord@mathworks.com

Hi Steve,

Thanks for replying !

Sorry about my initial post. I guarantee no typos in my script.

when I call "phis", its still a sym ... meaning I have not substituted
at value. I do that in the next step using subs(sym_dyPhi,some_value).

What next ?

Thanks,
P