compute integer base b logarithm - Maple Help

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ilog[b] - compute integer base b logarithm

ilog2 - compute integer base 2 logarithm

ilog10 - compute integer base 10 logarithm

Calling Sequence

ilog[b](x)

ilogbx

ilog2(x)

 

ilog10(x)

 

Parameters

b

-

positive real number

x

-

expression

Description

• 

These functions compute integer approximations to logarithms of x. They are  based on the IEEE function logb.

• 

The ilog[b](x) function approximates the integer base b logarithm, where the default base is exp(1).

• 

You can enter the command ilog[b] using either the 1-D or 2-D calling sequence. For example, ilog[2](50) is equivalent to ilog250.

• 

If x is real, ilog[b](x) returns r such that br|x|<br+1.

• 

The ilog2(x) function returns the integer base 2 logarithm of x.

  

If x is real and r = ilog2(x), then r is either an exact integer or special symbolic value, and 2r|x|<2r+1.

  

If x is a complex numeric, ilog2(x) returns  max(ilog2(Re(x)), ilog2(Im(x))).

  

If x is a special symbolic value, the indicated result is returned.

    1.  ilog2undefined&equals;undefined

    2.  ilog2± =

    3.  ilog2±0 =

• 

The ilog10(x) function returns the integer base 10 logarithm of x.

  

If x is real, ilog10(x) returns r such that r is either an exact integer or special symbolic value, and10r|x|<10r+1.

  

If x is a complex numeric, ilog10(x) returns  max(ilog10(Re(x)), ilog10(Im(x))).

  

If x is a special symbolic value, the indicated result is returned.

    1.  ilog10undefined&equals;undefined

    2.  ilog2± =

    3.  ilog2± =

• 

The computation of ilog2(x) and ilog10(x) is more efficient than ilog[b](x), b <> 2, 10.

Thread Safety

• 

The ilog2 and ilog10 commands are thread-safe as of Maple 15.

• 

For more information on thread safety, see index/threadsafe.

Examples

ilog10x

ilog10x

(1)

ilog10150

2

(2)

ilog101037

37

(3)

ilog10214&plus;310I

4

(4)

ilog250

5

(5)

ilog228

8

(6)

ilog310

2

(7)

ilog&ExponentialE;3

1

(8)

See Also

exceptions, float, initialfunctions, type


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