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Jan 24th, 2006

The problem with using Java's maths.cos()

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There are two things which I didn't or could not achieve with using maths.cos() from Java.

First - When I calculate cos90 or cos270, it gives me absurb values. It should be 0. Meaning it cannot calculate if the angle lies on X axis.

I tested with 91 or 271, gives a near 0 which is correct.

Second - I was figuring how do I include the number of terms to be calculated with my Cosine formula....

Lastly, I am using JFrames as my GUI and I can only properly exit from my menu bar. And not from the X button at top RH corner.

I would appreciate hints or guidance in solving the above 3 issues. Thank you so much people!

LiBOC

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Jan 24th, 2006

Re: The problem with using Java's maths.cos()

Math.cos is using angles in radians. Try Math.cos(Math.toRadians(90)).

Second - I don't understand.

Try jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

dandan

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Jan 24th, 2006

Re: The problem with using Java's maths.cos()

If you properly set up the application you can exit the application normally (with JVM shutdown) by using the operating system supplied features (like the close icon in the window corner) as well.

Something like

Java Syntax (Toggle Plain Text)
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

in your main application frame should work wonders.

jwenting

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duckman

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Jan 24th, 2006

Re: The problem with using Java's maths.cos()

Hi eveyone,

Quote originally posted by LiBOC ...

Second - I was figuring how do I include the number of terms to be calculated with my Cosine formula

Use loops and arrays

Richard West

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Jan 24th, 2006

Re: The problem with using Java's maths.cos()

Yea, I had convert it into radians before putting it back into the default math.cos() method... but only 270 and 90 are wrong values!

Quote originally posted by dandan ...

Math.cos is using angles in radians. Try Math.cos(Math.toRadians(90)).

Second - I don't understand.

Try jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

LiBOC

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Jan 25th, 2006

Re: The problem with using Java's maths.cos()

no, the rest is wrong as well (though it is possible that by some chance a few distinct values might happen to be identical it's unlikely).
But they're less obviously wrong unless you know what to expect. Do you know the exact cosine of every angle to 10 decimal places without looking them up?

jwenting

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duckman

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Jan 25th, 2006

Re: The problem with using Java's maths.cos()

Thanks.

I used the calculator program on my WinXP to counter check with my Java App. It is exactly correct. Only for 90 and 270 degrees. I also had converted them to radians.

And also, math.cos() method do not include terms if I am not wrong?

What if I want to write my own cosine formula that include a user-defined number of terms? Rewrite the formula into a java language? Solve the maths equation yourself?

can math.cos() do that?

Quote originally posted by jwenting ...

no, the rest is wrong as well (though it is possible that by some chance a few distinct values might happen to be identical it's unlikely).
But they're less obviously wrong unless you know what to expect. Do you know the exact cosine of every angle to 10 decimal places without looking them up?

LiBOC

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Jan 25th, 2006

Re: The problem with using Java's maths.cos()

What are the values you are getting for 90 and 270? Shouldn't they both be 0 according to the unit circle?

server_crash

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Jan 25th, 2006

Re: The problem with using Java's maths.cos()

Quote ...

What if I want to write my own cosine formula that include a user-defined number of terms? Rewrite the formula into a java language? Solve the maths equation yourself?

What do u want to do? I still have no clue? What do u mean by number terms? You aren't making much sense. Please give us an example. R u trying to solve generic equasions like:

Quote ...

1/2cos x =75

Quote ...

1/2cos(3x) -5cos = 45

iamthwee

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Jan 25th, 2006

Re: The problem with using Java's maths.cos()

Quote originally posted by server_crash ...

What are the values you are getting for 90 and 270? Shouldn't they both be 0 according to the unit circle?

yes, and when using radials they won't be 0 but roughly -.45 and +.98 respectively.

jwenting

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