java 对数和指数计算方式

public static void main(String[] args) throws InterruptedException{
    int a = 10;
    int b = 1000000;
    System.out.println(getlog(b,a));
   
}
static double getlog(int b,int a){
   return Math.log(b)/Math.log(a);
}

 public static void main(String[] args) throws InterruptedException{
        BigDecimal a = new BigDecimal(10);
        BigDecimal b = new BigDecimal(1000000);
        System.out.println(getlog(b,a));
//
    }
    static double getlog(BigDecimal b, BigDecimal a){
       return Math.log(b.doubleValue())/Math.log(a.doubleValue());
    }

    /**
     * Returns the natural logarithm (base <i>e</i>) of a {@code double}
     * value.  Special cases:
     * <ul><li>If the argument is NaN or less than zero, then the result
     * is NaN.
     * <li>If the argument is positive infinity, then the result is
     * positive infinity.
     * <li>If the argument is positive zero or negative zero, then the
     * result is negative infinity.</ul>
     *
     * <p>The computed result must be within 1 ulp of the exact result.
     * Results must be semi-monotonic.
     *
     * @param   a   a value
     * @return  the value ln&nbsp;{@code a}, the natural logarithm of
     *          {@code a}.
     */
    public static double log(double a) {
        return StrictMath.log(a); // default impl. delegates to StrictMath
    }
 
    /**
     * Returns the base 10 logarithm of a {@code double} value.
     * Special cases:
     *
     * <ul><li>If the argument is NaN or less than zero, then the result
     * is NaN.
     * <li>If the argument is positive infinity, then the result is
     * positive infinity.
     * <li>If the argument is positive zero or negative zero, then the
     * result is negative infinity.
     * <li> If the argument is equal to 10<sup><i>n</i></sup> for
     * integer <i>n</i>, then the result is <i>n</i>.
     * </ul>
     *
     * <p>The computed result must be within 1 ulp of the exact result.
     * Results must be semi-monotonic.
     *
     * @param   a   a value
     * @return  the base 10 logarithm of  {@code a}.
     * @since 1.5
     */
    public static double log10(double a) {
        return StrictMath.log10(a); // default impl. delegates to StrictMath
    }

double x = Math.log(10);

public class Logarithm {
    public static double log(double value, double base) {
        return Math.log(value) / Math.log(base);
    }
}

    public static void main(String[] args) {
        double log = log(27, 33);
        System.out.println(log);
    }
 
    private static double log(double value, double base) {
        return Logarithm.log(value) / Math.log(base);
    }

public static double log(double value, double base) {
        return Math.log10(value) / Math.log10(base);
}