logarithms - Maple Help
For the best experience, we recommend viewing online help using Google Chrome or Mozilla Firefox.

Online Help

All Products    Maple    MapleSim


simplify/ln

simplify expressions involving logarithms

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

simplify(expr, ln)

Parameters

expr

-

any expression

ln

-

literal name; ln

Description

• 

The simplify/ln function is used to simplify logarithmic expressions. It applies the following simplifications whenever it can determine that the appropriate conditions hold:

 

 

Simplification

Provided

 

 

ln⁡ab ==> b⁢ln⁡a

signum⁡a=1 and b is real

ln⁡ab ==> b⁢ln⁡−a

signum⁡a=−1 and b is even

ln⁡ab ==> b⁢ln⁡a

signum⁡a=−1 and b is odd

ln⁡ab ==> b⁢ln⁡a22

a is real and b is even

ln⁡ab ==> b⁢ln⁡a

a is real and b is odd

 

 

ln⁡x⁢y ==> ln⁡x+ln⁡y

0<x and signum⁡y is unknown

ln⁡x⁢y ==> ln⁡−x+ln⁡−y

signum⁡x=−1

ln⁡x⁢y ==> ln⁡−x+ln⁡y+I⁢π

signum⁡x=−1 and signum⁡y=1

 

 

ln⁡&ExponentialE;x ==> x

x is real

ln⁡LambertW⁡x ==> ln⁡x−LambertW⁡x

x is real

 

 

• 

In the case of an integer argument to ln, the integer is factored and the logarithm is returned as a sum of logarithms.

• 

In the case of a sum of terms as the argument to ln, the integer content of the sum is factored out and the logarithm is returned as a sum of two logarithms.

• 

Making the appropriate assumptions on the names in the expression to be simplified (see assume) provides simplify with enough information to apply the above identities correctly.

Examples

It is inappropriate to apply the above identities in these cases since nothing is known about n, x, and y:

> 

simplify⁡ln⁡x3&comma;ln

ln⁡x3

(1)
> 

simplify⁡ln⁡x⁢y

ln⁡x⁢y

(2)
> 

simplify⁡ln⁡exp⁡x&comma;ln

ln⁡&ExponentialE;x

(3)
> 

simplify⁡ln⁡yn&comma;ln

ln⁡yn

(4)

However, by making appropriate assumptions on the variables, enough information is provided to correctly apply the identities:

> 

assume⁡n&comma;even

> 

assume⁡x&comma;real

> 

assume⁡y<0

> 

simplify⁡ln⁡x3&comma;ln

ln⁡x~3

(5)
> 

simplify⁡ln⁡x⁢y

ln⁡−y~+ln⁡−x~

(6)
> 

simplify⁡ln⁡exp⁡x

x~

(7)
> 

simplify⁡ln⁡y3&comma;ln

3⁢ln⁡−y~+I⁢π

(8)
> 

simplify⁡ln⁡yn&comma;ln

n~⁢ln⁡−y~

(9)

Simplifications involving integer factors:

> 

simplify⁡ln⁡−40⁢a+15⁢b&comma;ln

ln⁡5+ln⁡−8⁢a+3⁢b

(10)
> 

simplify⁡ln⁡345366&comma;ln

ln⁡2+2⁢ln⁡3+ln⁡7+ln⁡2741

(11)

See Also

assume

combine

simplify