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

3 Ansichten (letzte 30 Tage)
Igor am 6 Jun. 2011
MATLAB
>> simplify(exp(log10(x)))
ans =
x^(1/log(10))
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...
##### 0 Kommentare-2 ältere Kommentare anzeigen-2 ältere Kommentare ausblenden

Melden Sie sich an, um zu kommentieren.

### Akzeptierte Antwort

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 KommentareKeine anzeigenKeine ausblenden
Walter Roberson am 7 Jun. 2011
Might have to be x::Real perhaps, instead of x::real
Igor am 7 Jun. 2011
Clearly.
But Log of complex value may be account like sin() with periodic term.
Thanks.

Melden Sie sich an, um zu kommentieren.

### Weitere Antworten (2)

Paulo Silva am 6 Jun. 2011
syms x
simplify(exp(log10(x)))
##### 1 Kommentar-1 ältere Kommentare anzeigen-1 ältere Kommentare ausblenden
Igor am 6 Jun. 2011
No, no :)
MATLAB works validly, you haven't seen ANS

Melden Sie sich an, um zu kommentieren.

Andrei Bobrov am 6 Jun. 2011
expand(subs(exp(log(10,x)),log(10,x)=ln(x)/ln(10)));
EDIT
rewrite(exp(log(10,x)),ln)
##### 1 Kommentar-1 ältere Kommentare anzeigen-1 ältere Kommentare ausblenden
Igor am 7 Jun. 2011
the last better..
thanks

Melden Sie sich an, um zu kommentieren.

### Kategorien

Mehr zu Common Operations finden Sie in Help Center und File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by