Logical error in Java programming

Question

case R.id.bTanx:
        temp=(float) (number/0.0174532925);
        num=Math.tan(temp);
        display.setText("Your Result is   " + num);

Guys I'm not able to get "Your Result is 1" when number = 45 ,by this code.Please help. As tan(45)=1 in degrees.i have converted it.but no desired result.

Where does Javascript or Eclipse come into this? You should look into the way you're converting degrees to radians, too... (hint: examine temp, and see whether it's what you expect) — Jon Skeet
– Jon Skeet, Commented Dec 19, 2013 at 10:51
Why is people downvoting this? Can't newbies join the community? — RamonBoza
– RamonBoza, Commented Dec 19, 2013 at 10:53
@RamonBoza I agree, I think the OP establishes a valid question, provides the information needed to solve it and demonstrates their attempt. It would have been nice to see a more complete example, however it does appear they are new. — Kevin Bowersox
– Kevin Bowersox, Commented Dec 19, 2013 at 10:55

Veger · Accepted Answer · 2013-12-19 11:38:45Z

4

To convert degrees to radian you first need to convert the degrees to a factor (of the circles circumference) by dividing by 360 degrees. Next you multiply by 2PI rad (which is the circumference of a 'unit circle').

When looking at the units you do this: degrees / degrees * radians = radians

So where you divide by 0.017 (2*PI / 360), you need to multiply instead:

temp = (float) (number * 0.0174532925);

Furthermore it is nicer (more clear) if you do not use 'magic numbers' and add comments (so people know what you are doing):

// Convert to rad
temp = (float) (number * 2 * Math.PI / 360);

And/or even use the available Java functionality:

// Convert to rad
temp = Math.toRadians(number);

edited Dec 19, 2013 at 11:38

answered Dec 19, 2013 at 10:51

Veger

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2 Comments

user3118200 Over a year ago

thankyou but this wont convert the number to radians. we convert degree to radians by radian= (degree )/ .0174

Veger Over a year ago

I added an explanation why you need to multiply instead of divide to my answer. Hopefully it will make it more clear what is going wrong.

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