expon

Name

expon --  Trace an exponential curve between specified points.

Description

Trace an exponential curve between specified points.

Syntax

ar expon ia, idur1, ib
kr expon ia, idur1, ib

Initialization

ia -- starting value. Zero is illegal for exponentials.

ib, ic, etc. -- value after dur1 seconds, etc. For exponentials, 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.

Performance

These units generate control or audio signals whose values can pass through 2 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 expon opcode. It uses the files expon.orc and expon.sco.

Example 15-1. Example of the expon opcode.

/* expon.orc */
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1

; Instrument #1.
instr 1
  ; Define kcps as a frequency value that exponentially declines 
  ; from 880 to 220. It declines over the period set by p3.
  kcps expon 880, p3, 220

  a1 oscil 20000, kcps, 1
  out a1
endin
/* expon.orc */
        
/* expon.sco */
; Table #1, a sine wave.
f 1 0 16384 10 1

; Play Instrument #1 for two seconds.
i 1 0 2
e
/* expon.sco */
        

See Also

expseg, expsegr, line, linseg, linsegr

Credits

Example written by Kevin Conder.