This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.

I've made it over many hurdles on this one, but since it's math intensive and I'm a graphical interface person, I'm having to bone up on my math. Let's say I'm calculating a negative exponent by dividing with BigDecimal. for(int i = 1; i > power; i--) { test= test.divide(Dholder,5000,BigDecimal.ROUND_HALF_UP); } This works fine, as long as there is no floating point on the power. But in some cases the power is something like, 223.0754233 I've tried separating the two, and using the right side as a percentage. e,g, (newPower = Dholder * rightSide, where Dholder is the base of the equation, then dividing one last time by the newPower) But when I test the result against a calculator, it's still not right. Although, it's close. Anybody know the correct formula for this? Thank you in advance, Tom

For division, you could divide the mantissas, then just subtract the two exponents. For Multiplication, multiply the mantissas, then add the exponents. Tom Blough

Tom Blough<br /> <blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Cum catapultae proscriptae erunt tum soli proscripti catapultas habebunt.<hr></blockquote>

Tom Clement
Greenhorn

Joined: Mar 21, 2004
Posts: 26

posted

0

Ok, concrete example: power = -5.300000190734863 base = 20 20 ^-5 = 3.125000E-7 using BigDecimal divide(). How do I calculate the .300000190734863 to arrive at correct answer of 1.2721571e-7 I'm using BigDecimal because of the size of some of the calculations. Oh, and I've tested the program on whole numbers and it works fine when tested against the calculator, it's the handling of the fractional part that's killing me. Thank you all, very much...... Tom