Changeset 910

Timestamp:

2015-06-09T14:24:57-07:00 (10 years ago)

Author:

Marek Rychlik

Message:

* empty log message *

File:

• branches/f4grobner/order.lisp (modified) (2 diffs)

branches/f4grobner/order.lisp

@@ -108 +108 @@
           (return-from invlex> (values nil nil))))))
 
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;
-;; Some globally-defined variables holding monomial orders
-;; and related macros/functions.
-;;
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(defvar *monomial-order* #'lex>
-  "Default order for monomial comparisons. This global variable holds
-the order which is in effect when performing polynomial
-arithmetic. The global order is called by the macro MONOMIAL-ORDER,
-which is somewhat more elegant than FUNCALL.")
-
-(defun monomial-order (x y)
-  "Calls the global monomial order function, held by *MONOMIAL-ORDER*."
-  (funcall *monomial-order* x y))
-
-(defun reverse-monomial-order (x y)
-  "Calls the inverse monomial order to the global monomial order function,
-held by *MONOMIAL-ORDER*."
-  (monomial-order y x))
+(defun reverse-monomial-order (order)
+  "Create the inverse monomial order to the given monomial order ORDER."
+  #'(lambda (x y) (funcall order y x)))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -136 +119 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-(defun elimination-order (primary-elimination-order secondary-elimination-order k)
-  "Return a predicate which compares monomials according to the
-K-th elimination order. The monomial orders PRIMARY-ELIMINATION-ORDER
-and SECONDARY-ELIMINATION-ORDER control the behavior on the first K
-and the remaining variables, respectively."
-  #'(lambda (p q &optional (start 0) (end (monom-dimension  p)))
-      (multiple-value-bind (primary equal)
-           (funcall primary-elimination-order p q start k)
-         (if equal
-             (funcall secondary-elimination-order p q k end)
-           (values primary nil)))))
+(defun make-elimination-order-maker (primary-elimination-order secondary-elimination-order)
+  "Return a function with a single integer argument K. This should be
+the number of initial K variables X[0],X[1],...,X[K-1], which precede
+remaining variables.  The call to the closure creates a predicate
+which compares monomials according to the K-th elimination order. The
+monomial orders PRIMARY-ELIMINATION-ORDER and
+SECONDARY-ELIMINATION-ORDER are used to compare the first K and the
+remaining variables, respectively, with ties broken by lexicographical
+order. That is, if PRIMARY-ELIMINATION-ORDER yields (VALUES NIL T),
+which indicates that the first K variables appear with identical
+powers, then the result is that of a call to
+SECONDARY-ELIMINATION-ORDER applied to the remaining variables
+X[K],X[K+1],..."
+  #'(lambda (k) 
+      #'(lambda (p q &optional (start 0) (end (monom-dimension  p)))
+          (multiple-value-bind (primary equal)
+              (funcall primary-elimination-order p q start k)
+            (if equal
+                (funcall secondary-elimination-order p q k end)
+                (values primary nil))))))
 
 (defun elimination-order-1 (secondary-elimination-order q &optional (start 0) (end (monom-dimension  p)))