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From: fang li on 10 Jun 2010 14:12
briefly, here an example,
C1=1+2*C(1,1);
C(1,1) is a symbol.
i try to get these numeric coefficients(say, 1 and 2) of a symbolic polynomial(C1). but i got a error
??? Error using ==> mupadmex
Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.

If the input expression contains a symbolic variable, use the VPA function instead.

Error in ==> sym.sym>sym.double at 927
Xstr = mupadmex('mllib::double', S.s, 0);

Error in ==> sym.sym2poly at 19
c = double(p);
and i try to add vpa(C1) to my code, it's still not work.
how should i fix the problem?
thanks a lot for any help.
From: Walter Roberson on 10 Jun 2010 14:38
fang li wrote:
> briefly, here an example, C1=1+2*C(1,1);
> C(1,1) is a symbol.
> i try to get these numeric coefficients(say, 1 and 2) of a symbolic
> polynomial(C1). but i got a error
> ??? Error using ==> mupadmex
> Error in MuPAD command: DOUBLE cannot convert the input expression into
> a double array.
>
> If the input expression contains a symbolic variable, use the VPA
> function instead.
>
> Error in ==> sym.sym>sym.double at 927
> Xstr = mupadmex('mllib::double', S.s, 0);
>
> Error in ==> sym.sym2poly at 19
> c = double(p);
> and i try to add vpa(C1) to my code, it's still not work.
> how should i fix the problem?

Use symvar and coeff or coeffs

See also
http://groups.google.ca/group/comp.soft-sys.matlab/browse_thread/thread/cca0ba1e62981e9e/48a9d3a3ded8b686
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