Merge pull request flintlib#300 from oscarbenjamin/pr_arb_repr

Fix arb.repr() and have it round trip

Author: oscarbenjamin

README.md

@@ -169,6 +169,8 @@ Contributors
 
 Changes
 
+- [gh-300](https://github.com/flintlib/python-flint/pull/300), Fix `arb.repr`
+  which now returns a Python representation that round trips. (OB)
 - [gh-289](https://github.com/flintlib/python-flint/pull/289),
   Add `.prec` attribute to series types `fmpz_series`, `fmpq_series`,
   `arb_series` and `acb_series`. (OB)

src/flint/test/test_all.py

@@ -1647,14 +1647,32 @@ def test_nmod_series():
 
 
 def test_arb():
-    A = flint.arb
-    assert A(3) > A(2.5)
-    assert A(3) >= A("2.5")
-    assert A(3) < A((3,1))
-    assert A(3) <= A("inf")
-    assert A(3) == A(3)
-    assert A(3) != A(2)
-    assert not (A("1.1") == A("1.1"))
+    arb = flint.arb
+    assert arb(3) > arb(2.5)
+    assert arb(3) >= arb("2.5")
+    assert arb(3) < arb((3,1))
+    assert arb(3) <= arb("inf")
+    assert arb(3) == arb(3)
+    assert arb(3) != arb(2)
+    assert not (arb("1.1") == arb("1.1"))
+
+    assert arb(3).repr() == 'arb((0x3, 0x0))'
+    assert arb("nan").repr() == "arb('nan')"
+    assert arb(0, "inf").repr() == "arb(0.0, '+inf')"
+    assert arb((1,2), (3,4)).repr() == "arb((0x1, 0x2), (0x3, 0x4))"
+    assert arb(1, arb("inf")).repr() == "arb((0x1, 0x0), '+inf')"
+    assert arb(1, "inf").repr() == "arb((0x1, 0x0), '+inf')"
+    assert arb(1, "nan").repr() == "arb((0x1, 0x0), '+inf')"
+    assert arb("nan", 1).repr() == "arb('nan')"
+    assert arb("nan", "nan").repr() == "arb('nan')"
+
+    for a in [arb(2), arb((1,2), (3,4)), arb("nan"), arb(0, "inf")]:
+        assert eval(a.repr()).repr() == a.repr()
+
+
+def test_acb():
+    acb = flint.acb
+    assert acb(1, 2).repr() == "acb(arb((0x1, 0x0)), arb((0x1, 0x1)))"
 
 
 def test_pickling():
@@ -5038,6 +5056,7 @@ def test_all_tests():
     test_fq_default_poly,
 
     test_arb,
+    test_acb,
 
     test_pickling,
 

src/flint/types/arb.pxd

@@ -15,3 +15,5 @@ cdef class arb(flint_scalar):
     cpdef bint is_nan(self)
     cpdef bint is_exact(self)
     cpdef bint is_integer(self)
+
+    cdef tuple _to_arfs(self)

src/flint/types/arb.pyx

@@ -196,14 +196,21 @@ cdef class arb(flint_scalar):
         arb_clear(self.val)
 
     def __init__(self, mid=None, rad=None):
+        cdef arf _rad
+        cdef fmpz man, exp
         if mid is not None:
             if arb_set_python(self.val, mid, 1) == 0:
                 raise TypeError("cannot create arb from type %s" % type(mid))
         if rad is not None:
-            rad = arb(rad)
-            arb_add_error(self.val, (<arb>rad).val)
-            # rad = arf(rad)
-            # arb_add_error_arf(self.val, (<arf>rad).val)
+            if isinstance(rad, tuple):
+                # Set the radius exactly from tuple of ints so that
+                # eval(a.repr()) round trips.
+                _rad = arf(rad)
+                man, exp = _rad.man_exp()
+                mag_set_fmpz_2exp_fmpz(arb_radref(self.val), man.val, exp.val)
+            else:
+                rad = arb(rad)
+                arb_add_error(self.val, (<arb>rad).val)
 
     cpdef bint is_zero(self):
         return arb_is_zero(self.val)
@@ -385,10 +392,17 @@ cdef class arb(flint_scalar):
         else:
             return (0, man, int(exp), man.bit_length())
 
+    # Make this a public function?
+    cdef tuple _to_arfs(self):
+        cdef arf mid = arf.__new__(arf)
+        cdef arf rad = arf.__new__(arf)
+        arf_set(mid.val, arb_midref(self.val))
+        arf_set_mag(rad.val, arb_radref(self.val))
+        return (mid, rad)
+
     def repr(self):
-        mid = self.mid()
-        rad = self.rad()
-        if rad.is_zero():
+        mid, rad = self._to_arfs()
+        if rad.is_zero() or mid.is_nan():
             return "arb(%s)" % mid._repr_str()
         else:
             return "arb(%s, %s)" % (mid._repr_str(), rad._repr_str())

src/flint/types/arf.pyx

@@ -94,7 +94,8 @@ cdef class arf:
         if arf_is_zero(self.val):
             return "0.0"
         elif arf_is_finite(self.val):
-            return "(%s, %s)" % self.man_exp()
+            man, exp = self.man_exp()
+            return "(%s, %s)" % (hex(man), hex(exp))
         elif arf_is_pos_inf(self.val):
             return "'+inf'"
         elif arf_is_neg_inf(self.val):