logcurve — This opcode implements a formula for generating a normalised logarithmic curve in range 0 - 1. It is based on the Max / MSP work of Eric Singer (c) 1994.
Generates a logarithmic 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 it is treated as if it were 1.
The formula used to calculate the curve is:
log(x * (y-1)+1) / (log(y)
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 logcurve opcode. It uses the file logcurve.csd.
Example 528. Example of the logcurve 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 -d ;;;realtime output </CsOptions> <CsInstruments> sr = 48000 ksmps = 100 nchnls = 2 instr 1 ; logcurve test kmod phasor 1/p3 kout logcurve kmod, p4 printks "kmod = %f kout = %f\\n", 0.1, kmod, kout endin </CsInstruments> <CsScore> i1 0 10 2 i1 10 10 30 i1 20 10 0.5 e </CsScore> </CsoundSynthesizer>