Symbolic Math Toolbox VS MuPAD: example in advance of the first?

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MATLAB
>> simplify(exp(log10(x)))
ans =
x^(1/log(10))
MuPAD
simplify(exp(log(10,x)), ln)
No effect. How to force MuPAD to simplify truely? I used consider MATLAB Simb.Tbx as a reduced version of MuPAD? That is -- MATLAB calls the MuPAD functions...

Akzeptierte Antwort

Walter Roberson
Walter Roberson am 7 Jun. 2011
This is as documented here
Mathematically, log(b, b^y) = y holds true for any real y. This simplification is implemented for the following cases: i) b is a symbolic (indexed) identifier and y is of type Type::Real, ii) b is numerical and y is integer or rational.
and
Note that arithmetical rules such as log(b, x*y) = log(b, x) + log(b, y) are not valid throughout the complex plane. Use properties to mark identifiers as real and apply functions such as expand or simplify to manipulate expressions involving log. Cf. example 4.
So you could possibly use
simplify(exp(log(10,x))) assuming x::real
  2 Kommentare
Walter Roberson
Walter Roberson am 7 Jun. 2011
Might have to be x::Real perhaps, instead of x::real
Igor
Igor am 7 Jun. 2011
Clearly.
But Log of complex value may be account like sin() with periodic term.
Thanks.

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Weitere Antworten (2)

Paulo Silva
Paulo Silva am 6 Jun. 2011
syms x
simplify(exp(log10(x)))

Andrei Bobrov
Andrei Bobrov am 6 Jun. 2011
in MuPAD
expand(subs(exp(log(10,x)),log(10,x)=ln(x)/ln(10)));
EDIT
rewrite(exp(log(10,x)),ln)

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