Multiplication of unbalanced operands

Torbjorn Granlund tege at
Mon Nov 27 16:52:25 CET 2006

"Marco Bodrato" <bodrato at> writes:

  In the preprint we did not care much about signs and other details...
  Now I'd suggest some little modifications:
  Start: a0+ a1*x + a2*x^2 ; b0 + b1*x
  Eval: (exactly the same)
  v0  = a0*b0              #c0
  v1  = (a0+a1+a2)*(b0+b1) #c0+c1+c2+c3
  vm1 = (a0-a1+a2)*(b0-b1) #c0-c1+c2-c3 (this can be negative)
  vinf= b1*a2              #c3
  Interpolation: (all intermediate results are positive)
  vm1 <- (v1-vm1) / 2 # c0+c2
  v1  <- v1-vm1-vinf  # c1 
  vm1 <- vm1 - v0     # c2 
Do you have the corresponding convenient formulas for 4:2 (using the
Toom3 interpolation) by any chance?


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