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--Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
--All rights reserved.
--
--Redistribution and use in source and binary forms, with or without
--modification, are permitted provided that the following conditions are
--met:
--
--    - Redistributions of source code must retain the above copyright
--      notice, this list of conditions and the following disclaimer.
--
--    - Redistributions in binary form must reproduce the above copyright
--      notice, this list of conditions and the following disclaimer in
--      the documentation and/or other materials provided with the
--      distribution.
--
--    - Neither the name of The Numerical ALgorithms Group Ltd. nor the
--      names of its contributors may be used to endorse or promote products
--      derived from this software without specific prior written permission.
--
--THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
--IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
--TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
--PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
--OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
--EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
--PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
--PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
--LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
--NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
--SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

)abbrev package CRAPACK CRApackage
 
++ This package \undocumented{}
CRApackage(R:EuclideanDomain): Exports == Implementation where
  Exports == with
    modTree: (R,List R) -> List R
	++ modTree(r,l) \undocumented{}
    chineseRemainder: (List R, List R) -> R
    ++ chineseRemainder(lv,lm) returns a value \axiom{v} such that, if
    ++ x is \axiom{lv.i} modulo \axiom{lm.i} for all \axiom{i}, then
    ++ x is \axiom{v} modulo \axiom{lm(1)*lm(2)*...*lm(n)}.
    chineseRemainder: (List List R, List R) -> List R
    ++ chineseRemainder(llv,lm) returns a list of values, each of which
    ++ corresponds to the Chinese remainder of the associated element of
    ++ \axiom{llv} and axiom{lm}.  This is more efficient than applying
    ++ chineseRemainder several times.
    multiEuclideanTree: (List R, R) -> List R
	++ multiEuclideanTree(l,r) \undocumented{}
  Implementation == add

    BB:=BalancedBinaryTree(R)
    x:BB

    -- Definition for modular reduction mapping with several moduli
    modTree(a,lm) ==
      t := balancedBinaryTree(#lm, 0$R)
      setleaves!(t,lm)
      mapUp!(t,"*")
      leaves mapDown!(t, a, "rem")

    chineseRemainder(lv:List(R), lm:List(R)):R ==
      #lm ~= #lv => error "lists of moduli and values not of same length"
      x := balancedBinaryTree(#lm, 0$R)
      x := setleaves!(x, lm)
      mapUp!(x,"*")
      y := balancedBinaryTree(#lm, 1$R)
      y := mapUp!(copy y,x,#1 * #4 + #2 * #3)
      (u := extendedEuclidean(value y, value x,1)) case "failed" =>
        error "moduli not relatively prime"
      inv := u . coef1
      linv := modTree(inv, lm)
      l := [(u*v) rem m for v in lv for u in linv for m in lm]
      y := setleaves!(y,l)
      value(mapUp!(y, x, #1 * #4 + #2 * #3)) rem value(x)

    chineseRemainder(llv:List List(R), lm:List(R)):List(R) ==
      x := balancedBinaryTree(#lm, 0$R)
      x := setleaves!(x, lm)
      mapUp!(x,"*")
      y := balancedBinaryTree(#lm, 1$R)
      y := mapUp!(copy y,x,#1 * #4 + #2 * #3)
      (u := extendedEuclidean(value y, value x,1)) case "failed" =>
        error "moduli not relatively prime"
      inv := u . coef1
      linv := modTree(inv, lm)
      retVal:List(R) := []
      for lv in llv repeat
        l := [(u3*v) rem m for v in lv for u3 in linv for m in lm]
        y := setleaves!(y,l)
        retVal := cons(value(mapUp!(y, x, #1*#4+#2*#3)) rem value(x),retVal)
      reverse retVal

    extEuclidean: (R, R, R) -> List R
    extEuclidean(a, b, c) ==
      u := extendedEuclidean(a, b, c)
      u case "failed" => error [c, " not spanned by ", a, " and ",b]
      [u.coef2, u.coef1]

    multiEuclideanTree(fl, rhs) ==
      x := balancedBinaryTree(#fl, rhs)
      x := setleaves!(x, fl)
      mapUp!(x,"*")
      leaves mapDown!(x, rhs, extEuclidean)