Error Using MathFP class in Eclipse

I am tryin 开发者_运维百科to develop a game in j2m using eclipse. To handle floating point I have downloaded the MathFp class. I did the following steps i placed the mathFP.class file in net/jscience/math/kvm/ directory 1> Ziped the folder containig the downloaded class. 2> java build path->libraries->ADD jar->selected my zipped folder. 3> in the source code of my project i wrote import net.jscience.math.kvm.MathFP;

But when i compile it it shows NoClassDefFoundError

Ensure the relevant jar is checked in the "Java Build Path" -> "Order and Export" window.