Programmer Guide/Command Reference/EVAL/log: Difference between revisions
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Compute the logarithm of the argument ''x'' element by element. | Compute the logarithm of the argument ''x'' element by element. | ||
;Usage: | ;Usage: | ||
:{| class="cgtable | :{| class="cgtable" cellpadding="3" | ||
|- | |- | ||
|'''<code>log(<var>x</var> , <var>b</var>)</code>''' || general logarithm to base ''b'' | |'''<code>log(<var>x</var> , <var>b</var>)</code>''' || general logarithm to base ''b'' | ||
Revision as of 13:47, 6 April 2011
Compute the logarithm of the argument x element by element.
- Usage
log(x , b)general logarithm to base b log(x)common logarithm (base 10) ln(x)natural logarithm (base e) alias: log(x,e)ld(x)logarithm to the base 2 alias: log(x,2)
- x
- a scalar, vector or matrix; all elements must be greater than 0
- b
- the base of the logarithm; must be a positive number
- Result
- The result r has the same type as x and contains the logarithm of x to the specified base b, computed element by element.
- See also
- npow2, exp
- Note
- For the inverse function the operater ^ can be used; e.g.: 10^x, e^x, ...
Example:
#a := eval vv(1,2,3,4,5) #b := eval init(5,2,0) #c := eval vmcol($#a, $#b, $#a) // -> $#c is a matrix with 4 rows and 5 columns: // $#c[*,*] = $#a, #c[1,*] = $#b[*,0], $#c[2,*] = $#b[*,1], $#c[3,*] = $#a
