expcurve — This opcode implements a formula for generating a normalised exponential curve in range 0 - 1. It is based on the Max / MSP work of Eric Singer (c) 1994.
Generates an exponential curve in range 0 to 1 of arbitrary steepness. Steepness index less than 1.0 would result in Not-a-Number errors and cause unstable behavior so is treated as if it were 1.
The formula used to calculate the curve is:
(exp(x * log(y))-1) / (y-1)
where x is equal to kindex and y is equal to ksteepness.
kindex -- Index value. Expected range 0 to 1.
ksteepness -- Steepness of the generated curve. Values closer to 1.0 result in a straighter line while larger values steepen the curve.
kout -- Scaled output.
Here is an example of the expcurve opcode. It uses the file expcurve.csd.
Example 278. Example of the expcurve 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 Silent -odac -iadc -n ;;;realtime output </CsOptions> <CsInstruments> sr = 44100 ksmps = 1000 nchnls = 2 instr 1 ; logcurve test kmod phasor 1/p3 kout expcurve kmod, p4 printks "mod = %f out= %f\\n", 0.5, kmod, kout endin /*--- ---*/ </CsInstruments> <CsScore> i1 0 5 2 i1 5 5 5 i1 10 5 30 i1 15 5 0.5 e </CsScore> </CsoundSynthesizer>