Changeset 7709:0afe8168cfd9 for sage/rings/real_rqdf.pyx

Timestamp:

12/15/07 03:36:07 (5 years ago)

Author:

mabshoff@…

Branch:

default

Message:

Apply most of Paul's patch

File:

• sage/rings/real_rqdf.pyx (modified) (4 diffs)

sage/rings/real_rqdf.pyx

@@ -120 +120 @@
     isnan = 0
     # The most significant double
-    d[0] = mpfr_get_d(rr, GMP_RNDZ)    
+    # We use GMP_RNDN here, which guarantees an exact
+    # conversion if prec(rr) <= 4*53+3=215.
+    d[0] = mpfr_get_d(rr, GMP_RNDN)
     mpfr_init2(cur, 53)
     mpfr_init2(res, mpfr_get_prec(rr))
-    mpfr_set_d(cur, d[0], GMP_RNDZ)
-    mpfr_sub(res, rr, cur, GMP_RNDZ)
+    mpfr_set_d(cur, d[0], GMP_RNDN)
+    mpfr_sub(res, rr, cur, GMP_RNDN)
     # now we repeatedly find the most significant part of the remainder 
     for i from 1 <= i < 4:
-        d[i] = mpfr_get_d(res, GMP_RNDZ) 
-        mpfr_set_d(cur, d[i], GMP_RNDZ)
-        mpfr_sub(res, res, cur, GMP_RNDZ)
+        d[i] = mpfr_get_d(res, GMP_RNDN)
+        mpfr_set_d(cur, d[i], GMP_RNDN)
+        mpfr_sub(res, res, cur, GMP_RNDN)
     mpfr_clear(cur)
     mpfr_clear(res)
@@ -290 +292 @@
             if  x.parent().prec() > 212:
                 return self(x)
-                
+
         return self._coerce_try(x, [RR()])
 
@@ -1076 +1078 @@
         return K(repr(self))
 
-    def _mpfr_(self, K):
-        """
-        EXAMPLES:
-            sage: w = RQDF('2.345001').sqrt(); w
-            1.531339609622894852128128425884749978483262262653204338472911277
-            sage: w._mpfr_(RealField(212))
-            1.53133960962289485212812842588474997848326226265320433847291128
-            sage: RealField(212)(w)
-            1.53133960962289485212812842588474997848326226265320433847291128
-            sage: RealField(250)(w)
-            1.5313396096228948521281284258847499784832622626532043384729112770000000000
-        """
-        return K(repr(self))
-
     def _pari_(self):
         """
@@ -1239 +1227 @@
             sage: w = RQDF(-2).sqrt(); w
             1.41421356237309504880168872420969807856967187537694807317667974*I
+            sage: w = RQDF('2.345001').sqrt(); w
+            1.531339609622894852128128425884749978483262262653204338472911277
             sage: w = RQDF(2).sqrt(all=True); w
             [1.414213562373095048801688724209698078569671875376948073176679738,