Re: [pdf-devel] pdf_function.c

[jemarch]

   > Do a general formula to solve m-dimensional cubic splines
   > exist? Something like that (the link talks about multi-linear
   > interpolation):
   > http://kanushu.uwaterloo.ca/~tveldhui/papers/MAScThesis/node3
   >2.html
   Ah. "Interpolating a single value  involves  2^D function 
   values  - one function value for each node in the enclosing 
   element."

   This explains the warnings in the spec:

   "The dimensionality of a sampled function is restricted only by 
   implementation limits. However, the number of samples required 
   to represent functions with high dimensionality multiplies 
   rapidly unless the sampling resolution is very low. Also,
   the process of multilinear interpolation becomes computationally 
   intensive if the number of inputs m is greater than 2.
   The multidimensional spline interpolation is even more 
   computationally intensive"

Yes. The tricky part is to extract a pair of interpolation functions
for each dimension from the samples array.

   > I have finished an implementation of type 2 functions.
   > Many thanks!
   Shall I send a patch for review?

I would wait to have the types 0, 2 and 3 (stitching functions works
with type 1 and type 0 functions) implemented. 

The type 4 functions (postscript calculator) requires a postscript
stack, a mini-parser to read values, operators and { } from the
stream, and is diffent enough to install it separately.

   > BTW: are you using the `pdf_stm_peek' function? 
   Not yet :-) pdf_create_func_2() uses only a dictionary.
   I intend to store the sample table as byte array, reading it 
   from a stream is *very* simple.

Ok.

-- 
Jose E. Marchesi  <address@hidden>
                  <address@hidden>

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