Math.pow

Hi all, I've got a simple question:4 to the power of 29 is 288230376151711744.The following results in 288230376151711740 though.double t=Math.pow(4,29);Why? (Writing your own pow-method naturally solves the problem, but what's happening here?)

[281 byte] By [cyberdaemon22222a] at [2007-11-27 8:43:23]

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# 1

you're running up against the innate imprecision of double.

petes1234a at 2007-7-12 20:43:04 >

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# 2

consider using BigInteger and its pow function rather than double. http://java.sun.com/j2se/1.5.0/docs/api/java/math/BigInteger.html#pow(int)Message was edited by: petes1234

petes1234a at 2007-7-12 20:43:04 >

# 3

For instance:

public static void main(String[] args)

{

BigInteger myBigInt = new BigInteger("4");

BigInteger resultBigInt = myBigInt.pow(29);

double resultDbl = resultBigInt.doubleValue();

System.out.println("BigInteger Result: " + resultBigInt.toString());

System.out.println("Double Result:" + String.valueOf(resultDbl));

}

petes1234a at 2007-7-12 20:43:04 >

# 4

petes1234, thanks a lot for your quick and clear reply.

cyberdaemon22222a at 2007-7-12 20:43:04 >

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