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Math.log problem in JDK1.4
Joined: Apr 30, 2007
Dec 22, 2008 02:54:00
While calculating logarithm values in JDK1.4 it returns some unpredicted values. As Math.log() returns double so there is loss of precision and exact log base 10 values cannot be calculated.
For a CR in TP, a formula was given as:
DispCode = Int ( -1 * log10( abs(LsbRsln)))
which is written in
int dispcode = (int) (-1 * (Math.log(Math.abs(Double.parseDouble(lsbrsln))) / Math.log(10)));
For example, if lsbrsln = 0.001, the formula is expected to return 3, instead it returns 2. The following part of the formula
Math.log (Math.abs (Double.parseDouble(0.001))) / Math.log(10) is returning -2.999999� and finally the formula is returning 2 while casting it into int.
In JDK1.5 we have Math.log10 method itself for calculating logbase10 values. But since we need to support JDK1.4 also we were not able to use that also.
Please let me know if you have the solution.
Joined: Mar 22, 2005
Dec 22, 2008 03:30:00
Please do not post the same question multiple times. Let's continue the discussion in this
, where you have an answer already.
subject: Math.log problem in JDK1.4
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