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173
SECTION 3.9 Functions
The Size value for an input dimension can be 1, in which case all input values in
that dimension will be mapped to the single allowed value. If Size is less than 4,
cubic spline interpolation is not possible and Order 3 will be ignored if specified.
+1 +1
Range
Range
0 0
1 2 3 4 5 7 8 9 10 11 12 13 14 15 1 2 3 4 6 7 8 9 10 11 12 13 14 15
Samples Samples
-1 -1
/Decode [-1 1] /Decode [-1 1.1429]
FIGURE 3.8 Mapping with the Decode array
3.9.2 Type 2 (Exponential Interpolation) Functions
Type 2 functions (PDF 1.3) include a set of parameters that define an exponential
interpolation of one input value and n output values:
f ( x ) = y0 , … , yn – 1
In addition to the entries in Table 3.35 on page 168, a type 2 function dictionary
includes those listed in Table 3.37. (See implementation note 41 in Appendix H.)
TABLE 3.37 Additional entries specific to a type 2 function dictionary
KEY TYPE VALUE
C0 array (Optional) An array of n numbers defining the function result when x = 0.0. Default value:
[ 0.0 ].
C1 array (Optional) An array of n numbers defining the function result when x = 1.0. Default value:
[ 1.0 ].
N number (Required) The interpolation exponent. Each input value x will return n values, given by
yj = C0j + xN × (C1j − C0j ), for 0 ≤ j < n.
Values of Domain must constrain x in such a way that if N is not an integer, all
values of x must be non-negative, and if N is negative, no value of x may be zero.
Typically, Domain is declared as [ 0.0 1.0 ], and N is a positive number. The Range
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