Java Reference
In-Depth Information
The parameter for
sin
,
cos
, and
tan
is an angle in radians. The return value for
asin
,
acos
, and
atan
is a degree in radians in the range between
-p
/2 and
p
/2. One degree is
equal to
p
/180 in radians, 90 degrees is equal to
p
/2 in radians, and 30 degrees is equal to
p
/6 in radians.
For example,
Math.toDegrees(Math.PI /
2
)
returns
90.0
Math.toRadians(
30
)
returns
0.5236
(same as π/6)
Math.sin(
0
)
returns
0.0
Math.sin(Math.toRadi
ans
(
270
))
returns
-1.0
Math.sin(Math.PI /
6
)
returns
0.5
Math.sin(Math.PI /
2
)
returns
1.0
Math.cos(
0
)
returns
1.0
Math.cos(Math.PI /
6
)
returns
0.866
Math.cos(Math.PI /
2
)
returns
0
Math.asin(
0.5
)
returns
0.523598333
(same as π/6)
Math.acos(
0.5
)
returns
1.0472
(same as π/3)
Math.atan(
1.0
)
returns
0.785398
(same as π/4)
4.2.2 Exponent Methods
There are five methods related to exponents in the
Math
class as shown in Table 4.2.
T
ABLE
4.2
Exponent Methods in the Math Class
Method
Description
Returns e raised to power of x (e
x
).
exp(x)
Returns the natural logarithm of x (ln(x)
=
log
e
(x)).
log(x)
Returns the base 10 logarithm of x (log
10
(x)).
log10(x)
Returns a raised to the power of
b
(a
b
).
pow(a, b)
sqrt(x)
Returns the square root of x (
2
x
) for x
7 =
0.
For example,
Math.exp(
1
)
returns
2.71828
Math.log(Math.E)
returns
1.0
Math.log10(
10
)
returns
1.0
Math.pow(
2
,
3
)
returns
8.0
Math.pow(
3
,
2
)
returns
9.0
Math.pow(
4.5
,
2.5
)
returns
22.91765
Math.sqrt(
4
)
returns
2.0
Math.sqrt(
10.5
)
returns
4.24
4.2.3 The Rounding Methods
The
Math
class contains five rounding methods as shown in Table 4.3.
T
ABLE
4.3
Round
ing Methods in the Math Class
Method
Description
ceil(x)
x is rounded up to its nearest integer. This integer is returned as a double value.
floor(x)
x is rounded down to its nearest integer. This integer is returned as a double value.
rint(x)
x is rounded up to its nearest integer. If x is equally close to two integers, the even one is returned as a double value.
Returns (int)Math.floor(x
+
0.5) if x is a float and returns (long)Math.floor(x
+
0.5) if x is a double.
round(x)
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