com.sun.squawk.util
Class MathUtils
java.lang.Object
com.sun.squawk.util.MathUtils
public class MathUtils
- extends Object
The class MathUtils
contains some of the Java SE Math routines that are not present in the CLDC 1.1 version of Math
:
asin(double)
, acos(double)
, atan(double)
& atan2(double, double)
.
The methods in this class are directly substitutable for the corresponding methods in Java SE java.lang.Math (circa JDK 1.2).
- See Also:
- java.lang.Math in Java SE,
CLDC 1.1's java.lang.Math
Method Summary |
static double |
acos(double a)
Returns the arc cosine of an angle, in the range of 0 through pi. |
static double |
asin(double a)
Returns the arc sine of an angle, in the range of -pi/2 through pi/2. |
static double |
atan(double a)
Returns the arc tangent of an angle, in the range of -pi/2 through pi/2. |
static double |
atan2(double y,
double x)
Converts rectangular coordinates (x, y) to polar (r, theta). |
static double |
exp(double a)
Returns Euler's number e raised to the power of a
double value. |
static double |
expm1(double a)
Returns ex -1. |
static double |
IEEEremainder(double x,
double p)
Computes the remainder operation on two arguments as prescribed
by the IEEE 754 standard. |
static double |
log(double a)
Returns the natural logarithm (base e) of a double
value. |
static double |
log1p(double a)
Returns the natural logarithm of the sum of the argument and 1. |
static double |
pow(double x,
double y)
Returns the value of the first argument raised to the power of the
second argument. |
static double |
rint(double a)
Returns the double value that is closest in value
to the argument and is equal to a mathematical integer. |
static long |
round(double a)
Returns the closest long to the argument. |
static int |
round(float a)
Returns the closest int to the argument. |
static double |
scalbn(double x,
int n)
performs x*2^n by exponent manipulation |
IEEEremainder
public static double IEEEremainder(double x,
double p)
- Computes the remainder operation on two arguments as prescribed
by the IEEE 754 standard.
The remainder value is mathematically equal to
f1 - f2
× n,
where n is the mathematical integer closest to the exact
mathematical value of the quotient f1/f2
, and if two
mathematical integers are equally close to f1/f2
,
then n is the integer that is even. If the remainder is
zero, its sign is the same as the sign of the first argument.
Special cases:
- If either argument is NaN, or the first argument is infinite,
or the second argument is positive zero or negative zero, then the
result is NaN.
- If the first argument is finite and the second argument is
infinite, then the result is the same as the first argument.
- Parameters:
x
- the dividend.p
- the divisor.
- Returns:
- the remainder when
f1
is divided by
f2
.
acos
public static double acos(double a)
- Returns the arc cosine of an angle, in the range of 0 through pi.
Special cases:
- If the argument is NaN or its absolute value is greater than 1, then the result is NaN.
- Parameters:
a
- the value whose arc cosine is to be returned.
- Returns:
- the arc cosine of the argument.
asin
public static double asin(double a)
- Returns the arc sine of an angle, in the range of -pi/2 through pi/2.
Special cases:
- If the argument is NaN or its absolute value is greater than 1, then the result is NaN.
- If the argument is zero, then the result is a zero with the same sign as the argument.
- Parameters:
a
- the value whose arc sine is to be returned.
- Returns:
- the arc sine of the argument.
atan
public static double atan(double a)
- Returns the arc tangent of an angle, in the range of -pi/2 through pi/2.
Special cases:
- If the argument is NaN, then the result is NaN.
- If the argument is zero, then the result is a zero with the same sign as the argument.
- Parameters:
a
- the value whose arc tangent is to be returned.
- Returns:
- the arc tangent of the argument.
atan2
public static double atan2(double y,
double x)
- Converts rectangular coordinates (x, y) to polar (r, theta).
This method computes the phase theta by computing an arc tangent
of y/x in the range of -pi to pi. Special cases:
- If either argument is NaN, then the result is NaN.
- If the first argument is positive zero and the second argument is positive,
or the first argument is positive and finite and the second argument is positive infinity,
then the result is positive zero.
- If the first argument is negative zero and the second argument is positive,
or the first argument is negative and finite and the second argument is positive infinity,
then the result is negative zero.
- If the first argument is positive zero and the second argument is negative,
or the first argument is positive and finite and the second argument is negative infinity,
then the result is the double value closest to pi.
- If the first argument is negative zero and the second argument is negative,
or the first argument is negative and finite and the second argument is negative infinity,
then the result is the double value closest to -pi.
- If the first argument is positive and the second argument is positive zero or negative zero,
or the first argument is positive infinity and the second argument is finite,
then the result is the double value closest to pi/2.
- If the first argument is negative and the second argument is positive zero or negative zero,
or the first argument is negative infinity and the second argument is finite,
then the result is the double value closest to -pi/2.
- If both arguments are positive infinity, then the result is the double value closest to pi/4.
- If the first argument is positive infinity and the second argument is negative infinity,
then the result is the double value closest to 3*pi/4.
- If the first argument is negative infinity and the second argument is positive infinity,
then the result is the double value closest to -pi/4.
- If both arguments are negative infinity, then the result is the double value closest to -3*pi/4.
- Parameters:
y
- the ordinate coordinatex
- the abscissa coordinate
- Returns:
- the theta component of the point (r, theta) in polar coordinates
that corresponds to the point (x, y) in Cartesian coordinates.
exp
public static double exp(double a)
- Returns Euler's number e raised to the power of a
double
value. Special cases:
- If the argument is NaN, the result is NaN.
- If the argument is positive infinity, then the result is
positive infinity.
- If the argument is negative infinity, then the result is
positive zero.
A result must be within 1 ulp of the correctly rounded
result. Results must be semi-monotonic.
- Parameters:
a
- the exponent to raise e to.
- Returns:
- the value e
a
,
where e is the base of the natural logarithms.
expm1
public static double expm1(double a)
- Returns ex -1. Note that for values of
x near 0, the exact sum of
expm1(x)
+ 1 is much closer to the true
result of ex than exp(x)
.
Special cases:
- If the argument is NaN, the result is NaN.
- If the argument is positive infinity, then the result is
positive infinity.
- If the argument is negative infinity, then the result is
-1.0.
- If the argument is zero, then the result is a zero with the
same sign as the argument.
A result must be within 1 ulp of the correctly rounded
result. Results must be semi-monotonic. The result of
expm1
for any finite input must be greater than or
equal to -1.0
. Note that once the exact result of
ex
- 1 is within 1/2
ulp of the limit value -1, -1.0
should be
returned.
- Parameters:
a
- the exponent to raise e to in the computation of
ex
-1.
- Returns:
- the value e
x
- 1.
log
public static double log(double a)
- Returns the natural logarithm (base e) of a
double
value. Special cases:
- If the argument is NaN or less than zero, then the result
is NaN.
- If the argument is positive infinity, then the result is
positive infinity.
- If the argument is positive zero or negative zero, then the
result is negative infinity.
A result must be within 1 ulp of the correctly rounded
result. Results must be semi-monotonic.
- Parameters:
a
- a value
- Returns:
- the value ln
a
, the natural logarithm of
a
.
log1p
public static double log1p(double a)
- Returns the natural logarithm of the sum of the argument and 1.
Note that for small values
x
, the result of
log1p(x)
is much closer to the true result of ln(1
+ x
) than the floating-point evaulation of
log(1.0+x)
.
Special cases:
- If the argument is NaN or less than -1, then the result is
NaN.
- If the argument is positive infinity, then the result is
positive infinity.
- If the argument is negative one, then the result is
negative infinity.
- If the argument is zero, then the result is a zero with the
same sign as the argument.
A result must be within 1 ulp of the correctly rounded
result. Results must be semi-monotonic.
- Parameters:
a
- a value
- Returns:
- the value ln(
x
+ 1), the natural
log of x
+ 1
pow
public static double pow(double x,
double y)
- Returns the value of the first argument raised to the power of the
second argument. Special cases:
- If the second argument is positive or negative zero, then the
result is 1.0.
- If the second argument is 1.0, then the result is the same as the
first argument.
- If the second argument is NaN, then the result is NaN.
- If the first argument is NaN and the second argument is nonzero,
then the result is NaN.
- If
- the absolute value of the first argument is greater than 1
and the second argument is positive infinity, or
- the absolute value of the first argument is less than 1 and
the second argument is negative infinity,
then the result is positive infinity.
- If
- the absolute value of the first argument is greater than 1 and
the second argument is negative infinity, or
- the absolute value of the
first argument is less than 1 and the second argument is positive
infinity,
then the result is positive zero.
- If the absolute value of the first argument equals 1 and the
second argument is infinite, then the result is NaN.
- If
- the first argument is positive zero and the second argument
is greater than zero, or
- the first argument is positive infinity and the second
argument is less than zero,
then the result is positive zero.
- If
- the first argument is positive zero and the second argument
is less than zero, or
- the first argument is positive infinity and the second
argument is greater than zero,
then the result is positive infinity.
- If
- the first argument is negative zero and the second argument
is greater than zero but not a finite odd integer, or
- the first argument is negative infinity and the second
argument is less than zero but not a finite odd integer,
then the result is positive zero.
- If
- the first argument is negative zero and the second argument
is a positive finite odd integer, or
- the first argument is negative infinity and the second
argument is a negative finite odd integer,
then the result is negative zero.
- If
- the first argument is negative zero and the second argument
is less than zero but not a finite odd integer, or
- the first argument is negative infinity and the second
argument is greater than zero but not a finite odd integer,
then the result is positive infinity.
- If
- the first argument is negative zero and the second argument
is a negative finite odd integer, or
- the first argument is negative infinity and the second
argument is a positive finite odd integer,
then the result is negative infinity.
- If the first argument is finite and less than zero
- if the second argument is a finite even integer, the
result is equal to the result of raising the absolute value of
the first argument to the power of the second argument
- if the second argument is a finite odd integer, the result
is equal to the negative of the result of raising the absolute
value of the first argument to the power of the second
argument
- if the second argument is finite and not an integer, then
the result is NaN.
- If both arguments are integers, then the result is exactly equal
to the mathematical result of raising the first argument to the power
of the second argument if that result can in fact be represented
exactly as a
double
value.
(In the foregoing descriptions, a floating-point value is
considered to be an integer if and only if it is finite and a
fixed point of the method ceil
or,
equivalently, a fixed point of the method floor
. A value is a fixed point of a one-argument
method if and only if the result of applying the method to the
value is equal to the value.)
A result must be within 1 ulp of the correctly rounded
result. Results must be semi-monotonic.
- Parameters:
x
- the base.y
- the exponent.
- Returns:
- the value
ab
.
rint
public static double rint(double a)
- Returns the
double
value that is closest in value
to the argument and is equal to a mathematical integer. If two
double
values that are mathematical integers are
equally close, the result is the integer value that is
even. Special cases:
- If the argument value is already equal to a mathematical
integer, then the result is the same as the argument.
- If the argument is NaN or an infinity or positive zero or negative
zero, then the result is the same as the argument.
- Parameters:
a
- a double
value.
- Returns:
- the closest floating-point value to
a
that is
equal to a mathematical integer.
round
public static long round(double a)
- Returns the closest
long
to the argument. The result
is rounded to an integer by adding 1/2, taking the floor of the
result, and casting the result to type long
. In other
words, the result is equal to the value of the expression:
(long)Math.floor(a + 0.5d)
Special cases:
- If the argument is NaN, the result is 0.
- If the argument is negative infinity or any value less than or
equal to the value of
Long.MIN_VALUE
, the result is
equal to the value of Long.MIN_VALUE
.
- If the argument is positive infinity or any value greater than or
equal to the value of
Long.MAX_VALUE
, the result is
equal to the value of Long.MAX_VALUE
.
- Parameters:
a
- a floating-point value to be rounded to a
long
.
- Returns:
- the value of the argument rounded to the nearest
long
value. - See Also:
Long.MAX_VALUE
,
Long.MIN_VALUE
round
public static int round(float a)
- Returns the closest
int
to the argument. The
result is rounded to an integer by adding 1/2, taking the
floor of the result, and casting the result to type int
.
In other words, the result is equal to the value of the expression:
(int)Math.floor(a + 0.5f)
Special cases:
- If the argument is NaN, the result is 0.
- If the argument is negative infinity or any value less than or
equal to the value of
Integer.MIN_VALUE
, the result is
equal to the value of Integer.MIN_VALUE
.
- If the argument is positive infinity or any value greater than or
equal to the value of
Integer.MAX_VALUE
, the result is
equal to the value of Integer.MAX_VALUE
.
- Parameters:
a
- a floating-point value to be rounded to an integer.
- Returns:
- the value of the argument rounded to the nearest
int
value. - See Also:
Integer.MAX_VALUE
,
Integer.MIN_VALUE
scalbn
public static double scalbn(double x,
int n)
- performs x*2^n by exponent manipulation
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