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authorLukas Larsson <[email protected]>2011-11-01 10:10:31 +0100
committerLukas Larsson <[email protected]>2011-11-01 10:10:31 +0100
commitd5ebc4c1409284e0a343a64edf7d75308a1b3dd2 (patch)
treea863c845667a7a7dee0e4504c6b10aa1dfb5ed84 /system/doc
parent668e7f7d2f8bf01f281065c19dd37dda4a499751 (diff)
parentec153fa6d7ba58a741e18f36b12736ec55243d35 (diff)
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Merge branch 'lukas/erts/large_float_cmp/OTP-9497'
* lukas/erts/large_float_cmp/OTP-9497: Update documentation after changes in integer and float comparison Do small optimisation on platforms with 32 bit Eterm Add tests for equality checking Optimize comparison of huge floats and smaller bignums Add tests for comparing large floats and small bignums Cleanup double_to_bignum conversion code Update size of tmp cmp bignum buffer Expand tests for float and number comparison Update heauristic to work on halfword Add heauristics bignum vs float checks Optimise bugnum and small comparison Add float vs integer comparison tests Update integer and floating point number comparisons
Diffstat (limited to 'system/doc')
-rw-r--r--system/doc/reference_manual/expressions.xml14
1 files changed, 9 insertions, 5 deletions
diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml
index 644896cd7f..c24b1110a4 100644
--- a/system/doc/reference_manual/expressions.xml
+++ b/system/doc/reference_manual/expressions.xml
@@ -561,11 +561,15 @@ number &lt; atom &lt; reference &lt; fun &lt; port &lt; pid &lt; tuple &lt; list
<p>Lists are compared element by element. Tuples are ordered by
size, two tuples with the same size are compared element by
element.</p>
- <p>If one of the compared terms is an integer and the other a
- float, the integer is first converted into a float, unless the
- operator is one of =:= and =/=. If the integer is too big to fit
- in a float no conversion is done, but the order is determined by
- inspecting the sign of the numbers.</p>
+ <p>When comparing an integer to a float, the term with the lesser
+ precision will be converted into the other term's type, unless the
+ operator is one of =:= and =/=. A float is more precise than
+ an integer until all significant figures of the float are to the left of
+ the decimal point. This happens when the float is larger/smaller then
+ +/-9007199254740992.0. The conversion strategy is changed
+ depending on the size of the float because otherwise comparison of large
+ floats and integers would loose their transitivity.</p>
+
<p>Returns the Boolean value of the expression, <c>true</c> or
<c>false</c>.</p>
<p>Examples:</p>