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GEN Routines: Sine/Cosine Generators

GEN09, GEN10, GEN19

  f   #    time    size   9      pna    stra   phsa   pnb   strb   phsb . . .  
  f   #    time    size  10      str1   str2   str3   str4 . . . .  
  f   #    time    size  19      pna    stra   phsa   dcoa  pnb    strb  phsb  dcob  .  .  .  

Description

These subroutines generate composite waveforms made up of weighted sums of simple sinusoids. The specification of each contributing partial requires 3 pfields using GEN09, 1 using GEN10, and 4 using GEN19.

Initialization

size – number of points in the table. Must be a power of 2 or power-of-2 plus 1 (see f statement).

pna, pnb, etc. – partial no. (relative to a fundamental that would occupy size locations per cycle) of sinusoid a, sinusoid b, etc. Must be positive, but need not be a whole number, i.e., non-harmonic partials are permitted. Partials may be in any order.

stra, strb, etc. – strength of partials pna, pnb, etc. These are relative strengths, since the composite waveform may be rescaled later. Negative values are permitted and imply a 180 degree phase shift.

phsa, phsb, etc. – initial phase of partials pna, pnb, etc., expressed in degrees.

dcoa, dcob, etc. – DC offset of partials pna, pnb, etc. This is applied after strength scaling, i.e. a value of 2 will lift a 2-strength sinusoid from range [-2,2] to range [0,4] (before later rescaling).

str1, str2, str3, etc. – relative strengths of the fixed harmonic partial numbers 1,2,3, etc., beginning in p5. Partials not required should be given a strength of zero.

Note

These subroutines generate stored functions as sums of sinusoids of different frequencies. The two major restrictions on GEN10 that the partials be harmonic and in phase do not apply to GEN09 or GEN19.

In each case the composite wave, once drawn, is then rescaled to unity if p4 was positive. A negative p4 will cause rescaling to be skipped.

Examples

  f    1    0    1024      9    1    3      0    3    1    0    9   .3333    180 
  f    2    0    1024     19    .5   1    270    1 

f1 combines partials l, 3 and 9 in the relative strengths in which they are found in a square wave, except that partial 9 is upside down. f 2 creates a rising sigmoid [0 - 2]. Both will be rescaled.


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GEN Routines: Sine/Cosine Generators