Issues using Math class

[rpratt]

Hi,
Has anyone had the following problem?

When I run the following code (just using Notepad and my DOS prompt):

public class MathFunctionsApp2
{
public static void main(String[] args)
{

int b = -50;
double x = 25.0;
double y = 3.0;
double z = 4.0;

System.out.println("cbrt(x) = "+ Math.cbrt(x));

System.out.println("hypot(y,z) = "+ Math.hypot(y,z));

System.out.println("log10(y) = "+ Math.log10(y));

System.out.println("signum(b) = "+ Math.signum(b));

}

}

It won't compile - it doesn't like SOME of the mathematical functions provided by the Math Class. (See error note below)

MathFunctionsApp2.java:13: cannot resolve symbol
symbol : method cbrt (double)
location: class java.lang.Math
System.out.println("cbrt(x) = "+ Math.cbrt(x));
^
MathFunctionsApp2.java:15: cannot resolve symbol
symbol : method hypot (double,double)
location: class java.lang.Math
System.out.println("hypot(y,z) = "+ Math.hypot(y,z));
^
MathFunctionsApp2.java:17: cannot resolve symbol
symbol : method log10 (double)
location: class java.lang.Math
System.out.println("log10(y) = "+ Math.log10(y));
^
MathFunctionsApp2.java:19: cannot resolve symbol
symbol : method signum (int)
location: class java.lang.Math
System.out.println("signum(b) = "+ Math.signum(b));
^
4 errors

However, it will accept some of the other Mathematical functions, such as sqrt, max, exp, etc. (I just didn't include them here - but they do work!)

Oh, and I also CAN get it to run if I just use TextPad.

Would love any advice I can get!
Thanks.

[server_crash]

Well, none of those are functions in the math class.
You can find a list here:
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Math.html

I can help you with a few of those:
To get the cube root:

Math.pow(base,3);

To get log base 10 of X:

int answer = Math.log(x)/Math.log(10);

To get hypotenuse a little more work is needed:

Math.sqr((Math.pow(a,2)+Math.pow(b,2));

I think that will work, not sure.

I don't know what you want on your last thing though.

[rpratt]

Well, none of those are functions in the math class. You can find a list here: http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Math.html

I can help you with a few of those: To get the cube root:

Math.pow(base,3);

To get log base 10 of X:

int answer = Math.log(x)/Math.log(10);

To get hypotenuse a little more work is needed:

Math.sqr((Math.pow(a,2)+Math.pow(b,2));

I think that will work, not sure.

I don't know what you want on your last thing though.

But here's the weird thing - it DOES work with TextPad. Also - the way that I found these was from a "Java for Dummies" book. Doesn't it seem strange that it would work with TextPad?

Thanks for the website though - very useful!

PS The signum returns the sign of the argument. I have no idea why this is useful. Just was trying out what the book suggested...

[rpratt]

Aha!! I figured it out!!

The math functions I was looking at are new to Java's version 1.5.0_04!!

For the very latest list:

java.sun.com/j2se/1.5.0/docs/api/java/lang/Math.html

And.... it turns out that my path was still pointing to the old version of Java (1.4 etc), NOT 1.5.0!

Hope someone can make good use of this!

[server_crash]

I see what it is. TextPad must come with extra classes that make things easier. A lot of times you will get things like this. I know normally you'll find an easier class to help out with reading and writing data.

To get the sine of a number in the normal methods:

Math.sin(x);

You won't be able to use those methods you have unless TextPad actually came with them, or you download them. I would suggest using the normal classes though.

[rpratt]

I think you're right about TextPad. But, also, check out my above comment about the new version of Java - I think that's why the book was recommending these functions.

Thanks again for all your help!

[server_crash]

Sorry, we must have posted at the same time because I did'nt see that. But that's cool, I never checked 1.5's new Math features. It's good they added a few of those like log10.