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ACOS()
Arcus cosine of the argument
Syntax
ACOS( nCosine ) -> nRadiant
Arguments
<nCosine> the cosine of an angle
Returns
<nRadiant> the angle whose cosine is <nCosine>
Description
The function ACOS() is the inverse function of COS(). It takes a cosine value and returns the smallest(!) angle whose cosine equals to the argument. The return value is given in radiants (full angle equals 2*Pi – see DTOR() if you need to convert it into degress). Note, that <nCosine> must be between -1 and 1 and that <nRadiant> is always between 0 and PI().
Examples
? acos( 0.0 ) // --> PI() / 2
? acos( 0.5 ) // --> 1.04719...
Tests
acos( 0.0 ) == PI() / 2
acos( sqrt( 1 / 2 ) ) == PI() / 4
acos( 1.0 ) == 0.0
acos( -1.0 ) == PI()
acos( 0.0 ) == PI() / 2 // and not -PI()/2, although cos (-PI()/2) == 0.0 !
Compliance
ACOS() is compatible with CT3’s ACOS().
Platforms
All
Files
Source is trig.c, library is libct.
Seealso
SIN(), COS(), TAN(), COT(), ASIN(), ATAN(), ATN2(), SINH(), COSH(), TANH(), RTOD(), DTOR(), PI()
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