FastMath atan2 does not agree with StrictMath for special cases
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Key: MATH-494
URL: https://issues.apache.org/jira/browse/MATH-494
Project: Commons Math
Issue Type: Bug
Reporter: Sebb
Fix For: 2.2, 3.0
FastMath atan2 does not agree with StrictMath for special cases.
There are two sign problems:
atan2(double -0.0, double -Infinity) expected -3.141592653589793 actual
3.141592653589793 entries [1, 4]
atan2(double -0.0, double Infinity) expected -0.0 actual 0.0 entries [1, 5]
A lot of NaNs where there should be a valid return:
atan2(double -1.7976931348623157E308, double -1.7976931348623157E308) expected
-2.356194490192345 actual NaN entries [6, 6]
atan2(double -1.7976931348623157E308, double 1.7976931348623157E308) expected
-0.7853981633974483 actual NaN entries [6, 7]
atan2(double -1.7976931348623157E308, double -1.1102230246251565E-16) expected
-1.5707963267948968 actual NaN entries [6, 8]
atan2(double -1.7976931348623157E308, double 1.1102230246251565E-16) expected
-1.5707963267948966 actual NaN entries [6, 9]
atan2(double -1.7976931348623157E308, double -2.2250738585072014E-308) expected
-1.5707963267948968 actual NaN entries [6, 10]
atan2(double -1.7976931348623157E308, double 2.2250738585072014E-308) expected
-1.5707963267948966 actual NaN entries [6, 11]
atan2(double -1.7976931348623157E308, double -4.9E-324) expected
-1.5707963267948968 actual NaN entries [6, 12]
atan2(double -1.7976931348623157E308, double 4.9E-324) expected
-1.5707963267948966 actual NaN entries [6, 13]
atan2(double 1.7976931348623157E308, double -1.7976931348623157E308) expected
2.356194490192345 actual NaN entries [7, 6]
atan2(double 1.7976931348623157E308, double 1.7976931348623157E308) expected
0.7853981633974483 actual NaN entries [7, 7]
atan2(double 1.7976931348623157E308, double -1.1102230246251565E-16) expected
1.5707963267948968 actual NaN entries [7, 8]
atan2(double 1.7976931348623157E308, double 1.1102230246251565E-16) expected
1.5707963267948966 actual NaN entries [7, 9]
atan2(double 1.7976931348623157E308, double -2.2250738585072014E-308) expected
1.5707963267948968 actual NaN entries [7, 10]
atan2(double 1.7976931348623157E308, double 2.2250738585072014E-308) expected
1.5707963267948966 actual NaN entries [7, 11]
atan2(double 1.7976931348623157E308, double -4.9E-324) expected
1.5707963267948968 actual NaN entries [7, 12]
atan2(double 1.7976931348623157E308, double 4.9E-324) expected
1.5707963267948966 actual NaN entries [7, 13]
atan2(double -1.1102230246251565E-16, double -1.7976931348623157E308) expected
-3.141592653589793 actual NaN entries [8, 6]
atan2(double -1.1102230246251565E-16, double 1.7976931348623157E308) expected
-0.0 actual NaN entries [8, 7]
atan2(double -1.1102230246251565E-16, double -4.9E-324) expected
-1.5707963267948968 actual NaN entries [8, 12]
atan2(double -1.1102230246251565E-16, double 4.9E-324) expected
-1.5707963267948966 actual NaN entries [8, 13]
atan2(double 1.1102230246251565E-16, double -1.7976931348623157E308) expected
3.141592653589793 actual NaN entries [9, 6]
atan2(double 1.1102230246251565E-16, double 1.7976931348623157E308) expected
0.0 actual NaN entries [9, 7]
atan2(double 1.1102230246251565E-16, double -4.9E-324) expected
1.5707963267948968 actual NaN entries [9, 12]
atan2(double 1.1102230246251565E-16, double 4.9E-324) expected
1.5707963267948966 actual NaN entries [9, 13]
atan2(double -2.2250738585072014E-308, double -1.7976931348623157E308) expected
-3.141592653589793 actual NaN entries [10, 6]
atan2(double -2.2250738585072014E-308, double 1.7976931348623157E308) expected
-0.0 actual NaN entries [10, 7]
atan2(double 2.2250738585072014E-308, double -1.7976931348623157E308) expected
3.141592653589793 actual NaN entries [11, 6]
atan2(double 2.2250738585072014E-308, double 1.7976931348623157E308) expected
0.0 actual NaN entries [11, 7]
atan2(double -4.9E-324, double -1.7976931348623157E308) expected
-3.141592653589793 actual NaN entries [12, 6]
atan2(double -4.9E-324, double 1.7976931348623157E308) expected -0.0 actual NaN
entries [12, 7]
atan2(double 4.9E-324, double -1.7976931348623157E308) expected
3.141592653589793 actual NaN entries [13, 6]
atan2(double 4.9E-324, double 1.7976931348623157E308) expected 0.0 actual NaN
entries [13, 7]
There are also some spurious errors, which are due to a bug in the test case -
expecting the values to be exactly the same as StrictMath
atan2(double 2.2250738585072014E-308, double -4.9E-324) expected
1.570796326794897 actual 1.5707963267948968 entries [11, 12]
atan2(double -2.2250738585072014E-308, double -4.9E-324) expected
-1.570796326794897 actual -1.5707963267948968 entries [10, 12]
atan2(double 1.1102230246251565E-16, double -2.2250738585072014E-308) expected
1.5707963267948968 actual 1.5707963267948966 entries [9, 10]
atan2(double -1.1102230246251565E-16, double -2.2250738585072014E-308) expected
-1.5707963267948968 actual -1.5707963267948966 entries [8, 10]
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