BigIntegerMath log10()函数|番石榴 |Java
Guava 的 BigIntegerMath 类的方法log10(BigInteger x, RoundingMode mode)返回 x 的以 10 为底的对数,根据指定的舍入模式进行舍入。
句法:
public static int log10(BigInteger x, RoundingMode mode)
参数:此方法采用以下参数:
- x :要查找其日志的 BigInteger 数。
- mode : 计算 10 对数的舍入模式。
返回值:该方法返回x的以10为底的对数,根据指定的舍入方式进行舍入。
异常:此方法引发以下异常:
- IllegalArgumentException:如果 x <= 0。
- ArithmeticException:如果 mode 是 RoundingMode.UNNECESSARY 并且 x 不是 10 的幂。
枚举舍入模式
Enum Constant | Description |
---|---|
CEILING | Rounding mode to round towards positive infinity. |
DOWN | Rounding mode to round towards zero. |
FLOOR | Rounding mode to round towards negative infinity. |
HALF_DOWN | Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round down. |
HALF_EVEN | Rounding mode to round towards the “nearest neighbor” unless both neighbors are equidistant, in which case, round towards the even neighbor. |
HALF_UP | Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round up. |
UNNECESSARY | Rounding mode to assert that the requested operation has an exact result, hence no rounding is necessary. |
UP | Rounding mode to round away from zero. |
下面的示例说明了 BigIntegerMath.log10() 方法:
示例 1:
// Java code to show implementation of
// log10(BigInteger x, RoundingMode mode) method
// of Guava's BigIntegerMath class
import java.math.*;
import com.google.common.math.BigIntegerMath;
class GFG {
// Driver code
public static void main(String args[])
{
BigInteger a1 = BigInteger.valueOf(10000);
// Using log10(BigInteger x, RoundingMode mode)
// method of Guava's BigIntegerMath class
// The RoundingMode HALF_EVEN rounds towards
// the "nearest neighbor" unless both neighbors
// are equidistant, in which case, round towards
// the even neighbor.
System.out.println("Log base 10 of " + a1
+ " with rounding mode HALF_EVEN = "
+ BigIntegerMath
.log10(a1,
RoundingMode.HALF_EVEN));
BigInteger a2 = BigInteger.valueOf(15);
// Using log10(BigInteger x, RoundingMode mode)
// method of Guava's BigIntegerMath class
// The RoundingMode HALF_DOWN rounds towards
// "nearest neighbor" unless both neighbors
// are equidistant, in which case round down.
System.out.println("Log base 10 of " + a2
+ " with rounding mode HALF_DOWN = "
+ BigIntegerMath
.log10(a2,
RoundingMode.HALF_DOWN));
}
}
输出:
Log base 10 of 10000 with rounding mode HALF_EVEN = 4
Log base 10 of 15 with rounding mode HALF_DOWN = 1
示例 2:显示 IllegalArgumentException
// Java code to show implementation of
// log10(BigInteger x, RoundingMode mode) method
// of Guava's BigIntegerMath class
import java.math.*;
import com.google.common.math.BigIntegerMath;
class GFG {
// Driver code
public static void main(String args[])
{
try {
BigInteger a1 = BigInteger.valueOf(-5);
// Using log10(BigInteger x, RoundingMode mode)
// method of Guava's BigIntegerMath class
// The RoundingMode HALF_EVEN rounds towards
// the "nearest neighbor" unless both neighbors
// are equidistant, in which case, round towards
// the even neighbor.
// This should throw "IllegalArgumentException"
// as a1 <= 0
System.out.println("Log base 10 of " + a1
+ " with rounding mode HALF_EVEN = "
+ BigIntegerMath
.log10(a1,
RoundingMode.HALF_EVEN));
}
catch (Exception e) {
System.out.println("Exception: " + e);
}
}
}
输出:
Exception: java.lang.IllegalArgumentException: x (-5) must be > 0
参考: https: Java