# ATN2()

Arcus tangent a sine and a cosine argument

Syntax

  ATN2 (nSine, nCosine) -> nRadiant

Arguments

  <nSine> the sine of an angle <nCosine> the cosine of an angle

Returns

  <nRadiant> the angle whose tangent is <nSine>/<nCosine>

Description

  The function ATN2() is an alternate function for calculating the arcus tangent, atn2(x,y) = atan(x/y). It takes two arguments, the sine and the cosine of the angle that should be calculated. Thus, in contrast to the ATAN() function, ATN2() can distinguish whether the sine or the cosine has a negative sign (or both being positive or negative), so that the return value can be between -PI() and PI() and covers the full angle. The return value is given in radiants (full angle equals 2*Pi - see DTOR() if you need to convert it into degress).

Examples

          ? atn2 (0.0, 1.0) --> 0.0
          ? atn2 (sqrt(1/2), sqrt(1/2)) --> PI()/4
    Tests
          atn2 (0.0, 1.0) == 0.0
          atn2 (sqrt(1/2),sqrt(1/2)) == PI()/4
          atn2 (-sqrt(1/2),-sqrt(1/2)) == -3/4*PI()  // atan() would return PI()/4 !

Status

  Ready

Compliance

  ATN2() is compatible with CT3's ATN2().

Platforms

  All

Files

  Source is trig.c, library is libct.

See Also

- SIN()
- COS()
- TAN()
- COT()
- ASIN()
- ACOS()
- ATAN()
- SINH()
- COSH()
- TANH()
- RTOD()
- DTOR()
- PI()