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javamathtrigonometry
Steph D
Steph D

Reputation: 1

Java netbeans Arctan wrong answer?

I tried using both but its giving me wrong answers, according to my calculator the answer should be:

arctan(0.35) = 19.29

What I used: 

Math.atan(Math.toRadians(angle)) and Math.atan();

Upvotes: 0

Views: 408

Answers (2)

jfcorugedo
jfcorugedo

Reputation: 10051

The methdo Math.atan() returns a result in radians:

Returns the arc tangent of a value; the returned angle is in the range -pi/2 through pi/2. Special cases:

If the argument is NaN, then the result is NaN. If the argument is zero, then the result is a zero with the same sign as the argument. The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

To obtain the value in degrees just perform a transformation:

@Test
public void arctan() {

    double result = Math.atan(0.35);

    assertThat(result*180/Math.PI).isBetween(19.29, 19.2901);
}

Upvotes: 0

Petr Janeček
Petr Janeček

Reputation: 38424

Your result is in degrees, not radians.

Math.toDegrees(Math.atan(0.35))

returns

19.290046219188735

which is your "expected" value. Make sure your inputs and outputs are in the correct unit!

Upvotes: 7

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