log
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## log

log — Returns a natural log of a number, or an array (with optional arbitrary base).

## Description

Returns the natural log of x (x positive only). In the case of an array input, the operation can have an optional arbitrary base.

The argument value is restricted for log, log10, and sqrt.

## Syntax

    log(x) (no rate
        restriction)

    log(k/i[]) (k- or i-arrays )

    kout[]log kin[],ibas

where the argument within the parentheses may be an expression. Value converters perform arithmetic translation from units of one kind to units of another. The result can then be a term in a further expression. In the case of an array input, ibas is the optional arbitrary base, which defaults to e (natural log base).

## Examples

Here is an example of the log opcode. It uses the file log.csd.

Example 477. Example of the log opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in
    -odac           -iadc    ;;;RT audio I/O
    ; For Non-realtime ouput leave only the line below:
    ; -o log.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Instrument #1.
    instr 1
      i1 = log(8)
      print i1
    endin

    </CsInstruments>
    <CsScore>

    ; Play Instrument #1 for one second.
    i 1 0 1
    e

    </CsScore>
    </CsoundSynthesizer>

Its output should include a line like this:

    instr 1:  i1 = 2.079

## See Also

abs, exp, frac, int, log10, i, sqrt

## Credits

Written by John ffitch.

New in version 3.47

Example written by Kevin Conder.

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