fix sizing at mul, truediv and floordiv when operands are complex.

Fix issue # 91

fxpmath/functions.py

@@ -366,9 +366,11 @@ def _mul_raw(x, y, n_frac):
     if not isinstance(y, Fxp):
         y = Fxp(y)
 
+    is_complex = x.vdtype == complex or y.vdtype == complex
+
     signed = x.signed or y.signed
     n_frac = x.n_frac + y.n_frac
-    n_word = x.n_word + y.n_word
+    n_word = x.n_word + y.n_word + int(is_complex)
     n_int = n_word - int(signed) - n_frac
     optimal_size = (signed, n_word, n_int, n_frac)
 
@@ -405,12 +407,13 @@ def _floordiv_raw_complex(x, y, n_frac):
     if not isinstance(y, Fxp):
         y = Fxp(y)
 
-    if x.vdtype == complex or y.vdtype == complex:
+    is_complex = x.vdtype == complex or y.vdtype == complex
+    if is_complex:
         _floordiv_repr = _floordiv_repr_complex
         _floordiv_raw = _floordiv_raw_complex
 
     signed = x.signed or y.signed
-    n_int = x.n_int + y.n_frac + signed
+    n_int = x.n_int + y.n_frac + int(signed) + int(is_complex)
     n_frac = 0
     n_word = int(signed) + n_int + n_frac
     optimal_size = (signed, n_word, n_int, n_frac)
@@ -444,12 +447,13 @@ def _truediv_raw_complex(x, y, n_frac):
     if not isinstance(y, Fxp):
         y = Fxp(y)
 
-    if x.vdtype == complex or y.vdtype == complex:
+    is_complex = x.vdtype == complex or y.vdtype == complex
+    if is_complex:
         _truediv_raw = _truediv_raw_complex
 
     signed = x.signed or y.signed
-    n_int = x.n_int + y.n_frac + signed
-    n_frac = x.n_frac + y.n_int
+    n_int = x.n_int + y.n_frac + int(signed) + int(is_complex)
+    n_frac = x.n_frac + y.n_int + int(is_complex)
     n_word = int(signed) + n_int + n_frac
     optimal_size = (signed, n_word, n_int, n_frac)
 

tests/test_issues.py

@@ -489,3 +489,16 @@ def test_issue_90_v0_4_9():
 
     assert np.all(x.val.shape == np.array((4,)))
     assert np.all(zz.val.shape == np.array((2,2)))
+
+
+def test_issue_91_v0_4_10():
+    # Inaccuracy for certain complex multiplications
+
+    x = Fxp(-1-1j)
+    xa = np.array(-1-1j)
+
+    y = x * x
+    ya = xa * xa
+
+    assert np.all(y() == ya)
+