[49] Need help with zeros

[Pat]

2^x-x^10 for zeros
2^x-x^10=0 for solve

Zeros Error:
Bad Argument Value
Solve Error:
Not reducible to a rational expression

I've tried various combinations of C/R and ~/= to no avail.
How can I find zeros or solve this expression?

The expression will graph and roots are attainable there:
-.9371 and 1.0776

Thanks.

[Pat]

Now found a hitherto unseen root at 58.77011

[John H Meyers]

Pat <ptm...@my-deja.com>:

> [solve] '2^X-X^10=0' (for all zeros)

Try (RPN mode, HP49G/48G):

\<< '2.^X-X^10.' 'X' -5. 75. 1. ROOTS \>>

Which will produce the answers:

{ -.937109201226 1.07755015 58.7701059379 }

Where ROOTS is a program (in UserRPL) found at
<http://hpcalc.org/math/misc/allroots.zip>

Or right here:

\<< \-> f x s e i
\<< { } { y x STO f
\->NUM y i + x STO f
\->NUM * 0. \<= { f x y
DUP i + 2. \->LIST ROOT
} IFT } 'y' s e i + i SEQ \>>
IF DUP SIZE THEN + SORT DUP 1.
\<< DUP2 SAME { DROP } IFT \>> DOLIST
SWAP DROP END \>> 'ROOTS' STO

Note that \<= means the "less than or equals" symbol (blue X), etc.

The arguments for ROOTS are the same as the arguments for SEQ;
see the documentation at the above URL for further explanation.

-----------------------------------------------------------
With best wishes from: John H Meyers <jhme...@mum.edu>

Sent via Deja.com http://www.deja.com/
Before you buy.

[Pat]

Thanks, John
Just what I was looking for.

[Steen S. Schmidt]

>>The expression will graph and roots are attainable there:
>>-.9371 and 1.0776
>

>Which are the exact two solutions NSOLVE finds

...and it warns of more possible solutions.

Regards
Steen

[Steen S. Schmidt]

>2^x-x^10 for zeros
>2^x-x^10=0 for solve
>
>Zeros Error:
>Bad Argument Value
>Solve Error:
>Not reducible to a rational expression

ZEROS and SOLVE only works for rational expression.

>I've tried various combinations of C/R and ~/= to no avail.
>How can I find zeros or solve this expression?
>

>The expression will graph and roots are attainable there:
>-.9371 and 1.0776

Which are the exact two solutions NSOLVE finds :-) NSOLVE is part of the
SymbToolz library here:
http://www.hpcalc.org/hp49/math/symbolic/symbtv11.zip

Regards
Steen