expsega
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## expsega

expsega — An exponential segment generator operating at a-rate.

## Description

An exponential segment generator operating at a-rate. This unit is almost identical to expseg, but more precise when defining segments with very short durations (i.e., in a percussive attack phase) at audio rate.

## Syntax

    ares expsega ia, idur1, ib [, idur2] [, ic] [...]

## Initialization

ia -- starting value. Zero is illegal.

ib, ic, etc. -- value after idur1 seconds, etc. must be non-zero and must agree in sign with ia.

idur1 -- duration in seconds of first segment. A zero or negative value will cause all initialization to be skipped.

idur2, idur3, etc. -- duration in seconds of subsequent segments. A zero or negative value will terminate the initialization process with the preceding point, permitting the last defined line or curve to be continued indefinitely in performance. The default is zero.

## Performance

This unit generate audio signals whose values can pass through two or more specified points. The sum of dur values may or may not equal the instrument's performance time. A shorter performance will truncate the specified pattern, while a longer one will cause the last defined segment to continue on in the same direction.

## Examples

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

Example 279. Example of the expsega 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    No messages
    -odac           -iadc     -d     ;;;RT audio I/O
    ; For Non-realtime ouput leave only the line below:
    ; -o expsega.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
      ; Define a short percussive amplitude envelope that
      ; goes from 0.01 to 20,000 and back.
      aenv expsega 0.01, 0.1, 20000, 0.1, 0.01

      a1 oscil aenv, 440, 1
      out a1
    endin

    </CsInstruments>
    <CsScore>

    ; Table #1, a sine wave.
    f 1 0 16384 10 1

    ; Play Instrument #1 for one second.
    i 1 0 1
    ; Play Instrument #1 for one second.
    i 1 1 1
    ; Play Instrument #1 for one second.
    i 1 2 1
    ; Play Instrument #1 for one second.
    i 1 3 1
    e

    </CsScore>
    </CsoundSynthesizer>

## See Also

expseg, triglinseg, trigexpseg, expsegr

## Credits

Author: Gabriel Maldonado

Example written by Kevin Conder.

New in Csound 3.57

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