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Beyond the basic arithmetic operations, a number of mathmatical
functions and constants are available from the Math
class as static methods and data.
We will discuss exactly what a class
is in Chapter 3:
Java and what static
means. For now just accept that "Math."
must preceed the function name.
Math is a class
in the default Java.lang
package (packages, i.e. Java libraries, will also be discussed later).
Note that the floating point arguments for the Math
functions can include not only finite number values but also, +/-infinity
and NaN.
See the description of the Math class in the Java
2 API Specifications for what happens when one or more of the
arguments for a function hold one of these exceptional values.
The Math
class offers:
- Trigonometric functions
(radian units):
Math.asin(double
y);
- Absolute values :
Math.abs(int
j);
Math.abs(long j);
Math.abs(float j);
Math.abs(double j);
- Random number
generators:
double
x = Math.random();
(generates values in the range 0.0
<= x < +1.0
)
- Other:
double
y = Math.sqrt(x);
double x = Math.exp(y);
Below is shown a table listing all the methods in the Math
class.
Java.lang.Math
Methods & Constants
Methods return double type value unless otherwise indicated.
See class
specifications for detailed description of each method. |
Constants
E - e, the base of the natural logarithm.
PI - pi
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Absolute Value
abs(double a)
abs(float a)- returns float
abs(int a)- returns int
abs(long a)- returns long |
Rounding
ceil(double a)- round up
floor(double a)- round downward
rint(double a)- round to nearest integer
round(double a)- round to nearest integer,
returns long
round(float a) - round to nearest integer,
returns int |
Maximum/Minimum
max(double a, double b) -
return larger of values a
and b
max(float
a, float b) -
return larger of values a
and b,
return float
max(long a, long b) - return larger of
values a and
b, return long
max(int
a, int b) - return larger of values a
and b,
return int
min(double
a, double b) -
return smaller of values a
and b
min(float
a, float b) -
return smaller of values a
and b,
return float
min(long a, long b) - return smaller
of values a and
b, return long
min(int
a, int b) - return smaller
of values a and
b, return int |
Trig Functions
cos(double
a)- argument in radians,
asin(double
a)- argument in radians
atan(double a)-
argument in radians |
Inverse Trig Functions
acos(double
a)- angle in radians, 0.0 through pi
asin(double a)- angle in radians, 0.0
through pi
atan(double a)- angle in radians, 0.0
through pi
atan2(double y, double x)- x,y point converted
to (r,theta) where theta angle in radians returned in
the range of -pi to pi |
|
Misc math functions
exp(double a) - ea, where e is the base
of the natural logarithm
log(double a)
- ln a, the natural logarithm of a
pow(double
a, double b)- the value of ab
sqrt(double a)
- squart root
IEEEremainder(double
f1, double f2) - remainder as prescribed by the IEEE
754 standard.
random()
- generate random value greater than or equal to 0.0 and less
than 1.0.
toRadians(double angdeg)- convert angdeg
in degrees to radians
toDegrees(double
angrad)- convert angrad
in radians to degrees
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Note: The
strictMath
class, added in version 1.3, holds the same static methods as the
Math class but must
always implement the same algorithms "Freely Distributable Math
Library" (fdlibm) and give the exact same results regardless of
the platform.
This differs from the Math
class implementations for which designers can optimise for particular
platforms. This means that calculations may give slightly different
results among different platforms and JVMs.
References & Web Resources
Latest update: Dec.12.2003
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