Kurzweil K2661 Musician's Manual page 565

output
values
+1
-1 1
-1
a = -1, b rising
from -1 to 1
Figure 17-11
warp4(a, b)
This equation, the Period Inverter,™ is based on repeated evaluations of the value of Input b.
The K2661 compares each new value of Input b with the value from the previous evaluation. If
the absolute value (always a positive number) of the difference between the two is greater than
the value of Input a, the current value of Input b is multiplied by -1.
The primary feature of this equation is that it will take a discontinuous signal and make it
continuous. If, for example, FUN1 uses an equation like a(y + b), its output can wrap around
from +1 to -1, or vice versa. You could set FUN1 as Input b for FUN2, set Input a of FUN2 to ON
(+1), and FUN2 would remove the discontinuity from the signal. The first graph below shows a
hypothetical output signal with such a discontinuity, and the second shows how FUN2 in this
case would make the signal continuous without drastically changing its shape.
If, on the other hand you want the signal to become discontinuous, you can use the warp4(a, b)
equation in a single FUN, with Input a set to OFF (0), and the signal would be multiplied by -1
with each evaluation of Input b.
-1
Figure 17-12
output
values
+1
input
-1
values
-1
a = .5, b rising
from -1 to 1
warp3(a, b)
output
values
+1
input
1
values
-1
discontinuous
input b signal
warp4(a, b)
output
values
+1
input
1 -1
values
-1
a =1, b rising
from -1 to 1
output
values
+1
-1
-1
same input b signal
with input a = 1
FUNS
The FUN Equations
input
1
values
input
1
values
17-13