Thread: simple netbeans project for math calculations with commons-math commons-math3-3.6.1.jar

Hi,

My name is Diana Mecum, and I am trying to learn Java. I have a master's degree in Math, and thought that working math problems might be interesting. The whole Java thing is a little overwhelming.

I have installed NetBeans on my Mac, and understand how to create projects with it. I understand how to import the commons-math3-3.6.1.jar flle into a newly created library for a new project.

I am trying to write a Java file to do simple math calculations, using the commons-math library files. I don't know how to import the library file within the Java file.

What I would like is a program to print output with a println command. I would then set up integers, doubles, etc, and perform various calculations with them. Can someone help me with a simple program to get started?

Diana M.

Hi,

NetBeans has a cool "Fix Imports" feature that I think you'll find very helpful.

double angle = Math.toRadians(90); // Convert degrees to radians	
Cos cos = new Cos(); // Compile error on this line: "Can't find symbol: class Cos"

At this point, NetBeans will show a compile error on the 2nd line. That's because it doesn't know which "Cos" class you're talking about (there could be many). Right-click an empty area of the text editor and select "Fix Imports" (or Ctrl + Shift + I). If the jar file is properly added to the project as a library (on the project's classpath), it should find the Cos class in the commons-math2-2.6.1.jar file and automatically add the import statement for you at the top of your class file:

import org.apache.commons.math3.analysis.function.Cos;

And now the compile error should be gone. If you've done any C/C++ coding before, these import statements are similar to "using namespace"; not to be confused with #include.

This will get the cosine of 90 degrees (in radians) and print it out:

double angle = Math.toRadians(90);		
Cos cos = new Cos();
double cosine = cos.value(angle);
 
System.out.println("Cosine of angle " + angle + " is " + cosine);

Hope that helps!

BinaryDigit09, thanks for your reply. Would it be possible to paste the entire file into the thread? I am not sure where to place the import line. I'll look at this tonight, and get back to you in 24 hours with a response as to whether I was able to get it working. Thanks again, Diana

Don't worry about where to place the import statement. NetBeans will do that for you when you tell it to "Fix Imports." But for your reference, it will go after the package statement and before the beginning of the class definition:

package myproject;
 
import org.apache.commons.math3.analysis.function.Cos; // <-- It's here!
 
public class Main {
	public static void main(String[] args) throws Exception {		
		double angle = Math.toRadians(90);
		Cos cos = new Cos();
		double cosine = cos.value(angle);
		System.out.println("Cosine of angle "+angle+" is " + cosine);		
	}	
}

I never manually type import statements. I always let NetBeans do it for me.

BinaryDigit09,

Thanks so much! I'll test it tomorrow morning, and get back to you with my results. Much appreciated. You have saved me a lot of time.

Diana M.

This worked, thanks a bunch!

Great!