FastMath nextAfter(double,double) bugs with special doubles
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Key: MATH-499
URL: https://issues.apache.org/jira/browse/MATH-499
Project: Commons Math
Issue Type: Bug
Affects Versions: 2.2, 3.0
Environment: Java 1.6
Reporter: Sebb
Assignee: Sebb
nextAfter(double, double) is added in StrictMath 1.6, so one needs to test with
Java 1.6 to see thi.
There are various boundary errors with nextAfter(double, double) - see below.
I think these are partially due to missing checks for special cases (e.g. the
NaNs), and partially due to the following code:
{code}
if (d * (direction - d) >= 0) {
// we should increase the mantissa
{code}
This appears to be a shorthand for
{code}
if ((d >=0) && (direction >= d))) {
// we should increase the mantissa
{code}
however the expression (direction - d) overlows for some double values, thus
causing the wrong branch to be taken.
double nextAfter(-0.0, -0.0) expected -0.0 actual 4.9E-324 entries [1, 1]
double nextAfter(-0.0, 0.0) expected 0.0 actual 4.9E-324 entries [1, 2]
double nextAfter(-0.0, NaN) expected NaN actual 4.9E-324 entries [1, 3]
double nextAfter(0.0, -0.0) expected -0.0 actual 4.9E-324 entries [2, 1]
double nextAfter(0.0, 0.0) expected 0.0 actual 4.9E-324 entries [2, 2]
double nextAfter(0.0, NaN) expected NaN actual 4.9E-324 entries [2, 3]
double nextAfter(-Infinity, NaN) expected NaN actual -Infinity entries [4, 3]
double nextAfter(Infinity, NaN) expected NaN actual Infinity entries [5, 3]
double nextAfter(-1.7976931348623157E308, NaN) expected NaN actual
-1.7976931348623155E308 entries [6, 3]
double nextAfter(1.7976931348623157E308, NaN) expected NaN actual
1.7976931348623155E308 entries [7, 3]
double nextAfter(-1.1102230246251565E-16, NaN) expected NaN actual
-1.1102230246251564E-16 entries [8, 3]
double nextAfter(1.1102230246251565E-16, NaN) expected NaN actual
1.1102230246251564E-16 entries [9, 3]
double nextAfter(-2.2250738585072014E-308, -0.0) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 1]
double nextAfter(-2.2250738585072014E-308, 0.0) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 2]
double nextAfter(-2.2250738585072014E-308, NaN) expected NaN actual
-2.225073858507201E-308 entries [10, 3]
double nextAfter(-2.2250738585072014E-308, 1.1102230246251565E-16) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 9]
double nextAfter(-2.2250738585072014E-308, 2.2250738585072014E-308) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 11]
double nextAfter(-2.2250738585072014E-308, -4.9E-324) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 12]
double nextAfter(-2.2250738585072014E-308, 4.9E-324) expected
-2.225073858507201E-308 actual -2.225073858507202E-308 entries [10, 13]
double nextAfter(2.2250738585072014E-308, -0.0) expected 2.225073858507201E-308
actual 2.225073858507202E-308 entries [11, 1]
double nextAfter(2.2250738585072014E-308, 0.0) expected 2.225073858507201E-308
actual 2.225073858507202E-308 entries [11, 2]
double nextAfter(2.2250738585072014E-308, NaN) expected NaN actual
2.225073858507201E-308 entries [11, 3]
double nextAfter(2.2250738585072014E-308, -1.1102230246251565E-16) expected
2.225073858507201E-308 actual 2.225073858507202E-308 entries [11, 8]
double nextAfter(2.2250738585072014E-308, -2.2250738585072014E-308) expected
2.225073858507201E-308 actual 2.225073858507202E-308 entries [11, 10]
double nextAfter(2.2250738585072014E-308, -4.9E-324) expected
2.225073858507201E-308 actual 2.225073858507202E-308 entries [11, 12]
double nextAfter(2.2250738585072014E-308, 4.9E-324) expected
2.225073858507201E-308 actual 2.225073858507202E-308 entries [11, 13]
double nextAfter(-4.9E-324, -0.0) expected -0.0 actual -1.0E-323 entries [12, 1]
double nextAfter(-4.9E-324, 0.0) expected -0.0 actual -1.0E-323 entries [12, 2]
double nextAfter(-4.9E-324, NaN) expected NaN actual -0.0 entries [12, 3]
double nextAfter(-4.9E-324, 1.1102230246251565E-16) expected -0.0 actual
-1.0E-323 entries [12, 9]
double nextAfter(-4.9E-324, 2.2250738585072014E-308) expected -0.0 actual
-1.0E-323 entries [12, 11]
double nextAfter(-4.9E-324, 4.9E-324) expected -0.0 actual -1.0E-323 entries
[12, 13]
double nextAfter(4.9E-324, -0.0) expected 0.0 actual 1.0E-323 entries [13, 1]
double nextAfter(4.9E-324, 0.0) expected 0.0 actual 1.0E-323 entries [13, 2]
double nextAfter(4.9E-324, NaN) expected NaN actual 0.0 entries [13, 3]
double nextAfter(4.9E-324, -1.1102230246251565E-16) expected 0.0 actual
1.0E-323 entries [13, 8]
double nextAfter(4.9E-324, -2.2250738585072014E-308) expected 0.0 actual
1.0E-323 entries [13, 10]
double nextAfter(4.9E-324, -4.9E-324) expected 0.0 actual 1.0E-323 entries [13,
12]
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