Changeset 1043

Timestamp:

2015-06-10T08:40:57-07:00 (9 years ago)

Author:

Marek Rychlik

Message:

* empty log message *

File:

• branches/f4grobner/parse.lisp (modified) (1 diff)

branches/f4grobner/parse.lisp

@@ -251 +251 @@
    (t (sort-poly-1 poly-or-poly-list order))))
 
-;; Return the standard basis of the monomials in n variables
-(defun variable-basis (ring n &aux (basis (make-list n)))
-  "Generate a list of polynomials X[i], i=0,1,...,N-1."
-  (dotimes (i n basis)
-    (setf (elt basis i) (make-variable ring n i))))
-
-(defun poly-eval-1 (expr vars &optional (ring *ring-of-integers*) (order #'lex>)
-                    &aux
-                      (ring-and-order (make-ring-and-order :ring ring :order order))
-                      (n (length vars))
-                      (basis (variable-basis ring (length vars))))
-  "Evaluate an expression EXPR as polynomial by substituting operators
-+ - * expt with corresponding polynomial operators and variables VARS
-with the corresponding polynomials in internal form.  We use special
-versions of binary operators $poly+, $poly-, $minus-poly, $poly* and
-$poly-expt which work like the corresponding functions in the POLY
-package, but accept scalars as arguments as well. The result is a
-polynomial in internal form.  This operation is somewhat similar to
-the function EXPAND in CAS."
-  (cond
-    ((numberp expr)
-     (cond
-       ((zerop expr) NIL)
-       (t (make-poly-from-termlist (list (make-term (make-monom :dimension n) expr))))))
-    ((symbolp expr)
-     (nth (position expr vars) basis))
-    ((consp expr)
-     (case (car expr)
-       (expt
-        (if (= (length expr) 3)
-            ($poly-expt ring-and-order
-                        (poly-eval-1 (cadr expr) vars ring order)
-                        (caddr expr)
-                        n)
-            (error "Too many arguments to EXPT")))
-       (/
-        (if (and (= (length expr) 3)
-                 (numberp (caddr expr)))
-            ($poly/ ring (cadr expr) (caddr expr))
-            (error "The second argument to / must be a number")))
-       (otherwise
-        (let ((r (mapcar
-                  #'(lambda (e) (poly-eval-1 e vars ring order))
-                  (cdr expr))))
-          (ecase (car expr)
-            (+ (reduce #'(lambda (p q) ($poly+ ring-and-order p q n)) r))
-            (-
-             (if (endp (cdr r))
-                 ($minus-poly ring (car r) n)
-                 ($poly- ring-and-order
-                         (car r)
-                         (reduce #'(lambda (p q) ($poly+ ring-and-order p q n)) (cdr r))
-                         n)))
-            (*
-             (reduce #'(lambda (p q) ($poly* ring-and-order p q n)) r))
-            )))))))
-
-             
-(defun poly-eval (expr vars &optional (order #'lex>) (ring *ring-of-integers*))
-  "Evaluate an expression EXPR, which should be a polynomial
-expression or a list of polynomial expressions (a list of expressions
-marked by prepending keyword :[ to it) given in Lisp prefix notation,
-in variables VARS, which should be a list of symbols. The result of
-the evaluation is a polynomial or a list of polynomials (marked by
-prepending symbol '[) in the internal alist form. This evaluator is
-used by the PARSE package to convert input from strings directly to
-internal form."
-  (cond
-   ((numberp expr)
-    (unless (zerop expr)
-      (make-poly-from-termlist 
-       (list (make-term (make-monom :dimension (length vars)) expr)))))
-   ((or (symbolp expr) (not (eq (car expr) :[)))
-    (poly-eval-1 expr vars ring order))
-   (t (cons '[ (mapcar #'(lambda (p) (poly-eval-1 p vars ring order)) (rest expr))))))
-
-
+
+