20.10

java.lang.Double

THE PACKAGE JAVA.LANG

20.10.22

public static double longBitsToDouble(long bits)

The argument is considered to be a representation of a floating point value accord 

ing to the IEEE 754 floating point  double format  bit layout. That floating point

value is returned as the result.

If the argument is

0x7f80000000000000L

, the result will be positive infinity.

If the argument is

0xff80000000000000L

, the result will be negative infinity.

If the argument is any value in the range

0x7ff0000000000001L

 through

0x7fffffffffffffffL

 or in the range

0xfff0000000000001L

 through

0xffffffffffffffffL

, the result will be NaN. (All IEEE 754 NaN values

are, in effect, lumped together by the Java language into a single value called

NaN.)

In all other cases, let

s

,

e

, and

m

 be three values that can be computed from the

argument:

int s = ((bits >> 63) == 0) ? 1 :  1;

int e = (int)((bits >> 52) & 0x7ffL);

long m = (e == 0) ?

(bits & 0xfffffffffffffL) << 1 :

(bits & 0xfffffffffffffL) | 0x10000000000000L;

Then the floating point result equals the value of the mathematical expression

s

m

2

e

  1075

.

Let beeves and home bred kine partake

The sweets of Burn mill meadow;

The swan on still St. Mary s Lake

Float double, swan and shadow!

 William Wordsworth,

Yarrow Unvisited

 (1803)

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