source: branches/f4grobner/ring.lisp@ 2818

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(defpackage "RING"

  (:use :cl)

  (:export "R-PARSE"

           "UNIT-ELEMENT"

           "R-ZEROP"

           "R+"

           "R-"

           "R*"

           "R+"

           "R/"

           "R-EXPT"

           "R-LCM"

           "R-EZGCD"

           "R-GCD"

           "R-TOTAL-DEGREE"

           "R-DIMENSION"

           "R-EXPONENTS"

           "R-COEFF"

           "R-SUGAR"

           "R-DIVIDES-P"   

           "R-DIVIDES-LCM-P"

           "R-LCM-DIVIDES-LCM-P"

           "R-LCM-EQUAL-LCM-P"

           "R-REL-PRIME-P"    

           "R-EQUALP"          

           "R-ELT"

           "R->LIST"

           "R-DIVISIBLE-BY-P"   

           "R-REL-PRIME-P"      

           "R-DEPENDS-P"        

           "R-TENSOR-PRODUCT"

           "R-CONTRACT"      

           "R-LENGTH"

           "MULTIPLY-BY"

           "ADD-TO"

           "SUBTRACT-FROM"

           "UNARY-MINUS"

           "SCALAR"

           "INSERT-ITEM"

           "APPEND-ITEM")

  (:documentation

   "Implements ring operations.  These are all operations that are

performed on the coefficients by the package, and thus the coefficient

ring can be changed by merely redefining these operations."))



(in-package :ring)



(defclass scalar () 

  ((value :initarg :value :accessor value))

  (:documentation "Wraps objects suitable as scalars/polynomial coefficients"))



(defgeneric unit-element (class))



(defgeneric r-zerop (object)

  (:method ((self number)) (zerop self))

  (:documentation "Tests whether a ring element is 0."))



(defgeneric r+ (x y)

  (:method ((x number) (y number)) (+ x y))

  (:documentation "Adds ring elements.")) 



(defgeneric r- (x y)

  (:method ((x number) (y number)) (- x y))

  (:documentation "Subtracts ring elements.")) 



(defgeneric r* (x y)

  (:method ((x number) (y number)) (* x y))

  (:documentation "Multiplies ring elements.")) 



(defgeneric r-tensor-product (x y)

  (:documentation "Takes a tensor product of two objects."))



(defgeneric r/ (x y)

  (:method ((x number) (y number)) (/ x y))

  (:documentation "Divides ring elements.")) 



(defgeneric r-lcm (x y)

  (:method ((x integer) (y integer)) (lcm x y))

  (:documentation "Returns the least common multiple of ring elements.")) 



(defgeneric r-expt (x y)

  (:method ((x integer) (y integer)) (expt x y))

  (:documentation "Raises X to power Y.")) 



(defgeneric r-ezgcd (x y)

  (:method ((x integer) (y integer)

            &aux (c (gcd x y)))

    (values c (/ x c) (/ y c)))

  (:documentation "Solves the diophantine system: X=C*X1, Y=C*X2,

C=GCD(X,Y).  It returns C, X1 and Y1. The result may be obtained by

the Euclidean algorithm."))



(defgeneric r-gcd (x y)

  (:method ((x integer) (y integer))

    (gcd x y))

  (:documentation "Returns GCD(X,Y)."))



(defgeneric r-dimension (object))

(defgeneric r-exponents (object))



(defgeneric r-coeff (object))

(defgeneric (setf r-coeff) (new-value object))



(defgeneric r-total-degree (object &optional start end))



(defgeneric r-divides-p (object1 object2)

  (:method ((object1 integer) (object2 integer))

    (zerop (rem object2 object1)))

  (:documentation "Returns T if OBJECT1 divides OBJECT2"))



(defgeneric r-divides-lcm-p (object1 object2 object3)

  (:documentation "Returns T if OBJECT divides LCM(OBJECT2, OBJECT3), NIL otherwise."))



(defgeneric r-lcm-divides-lcm-p (object1 object2 object3 object4)

  (:documentation "Returns T if LCM(OBJECT1,OBJECT2) divides LCM(OBJECT3,OBJECT4), NIL otherwise."))



(defgeneric r-lcm-equal-lcm-p (object1 object2 object3 object4)

  (:documentation "Returns T if object LCM(OBJECT1,OBJECT2) equals LCM(OBJECT3,OBJECT4), NIL otherwise."))



(defgeneric r-equalp (object1 object2)

  (:method (object1 object2) (equalp object1 object2))

  (:documentation "Equality using deep comparison of object slots."))



(defgeneric r-elt (object index))



(defgeneric (setf r-elt) (new-value object index))



(defgeneric r-length (object))



(defgeneric r->list (object))

(defgeneric r-sugar (object))

(defgeneric r-rel-prime-p (object1 object2))

(defgeneric r-contract (object k))

(defgeneric r-divisible-by-p (object1 object2))

(defgeneric r-depends-p (object k))



(defgeneric multiply-by (self other)

  (:method (self other) (r* self other)))



(defgeneric add-to (self other)

  (:documentation "Add to object SELF another object OTHER.  For

complex objects, it may destructively modify SELF and destructively

modify/invalidate object OTHER. For standard classes implementing this

method, the result should be an object which is EQ to SELF. For

built-in classes, such as NUMBER, the returned object may not be EQ to

the original, but it will be EQL to it.")

  (:method (self other) (r+ self other)))



(defgeneric subtract-from (self other)

  (:documentation "Subtract from an object SELF another object OTHER.

For complex objects, it may destructively modify SELF and

destructively modify/invalidate object OTHER. For standard classes

implementing this method, the result should be an object which is EQ

to SELF. For built-in classes, such as NUMBER, the returned object may

not be EQ to the original.")

  (:method (self other) (r- self other)))



(defgeneric unary-minus (self)

  (:method ((x number)) (- x)))



(defgeneric insert-item (self item))

(defgeneric append-item (self item))