FUNCTIONUnder review

ACos

ACos( <nCos> ) --> nRet

Calculates the inverse cosine in radians.

ACosAdvPL

01 · OVERVIEW

Overview

ACos receives an angle cosine within -1 to 1 and returns an angle from zero to PI radians. Its input is not degrees. Documentation describes an undefined result outside the domain; validate input rather than depending on an infinity representation. (TOTVS, n.d., ref. 1)

02 · SYNTAX

Syntax

ACos( <nCos> ) --> nRet

Parameters

nCos

NumericRequired

Cosine within the closed interval [-1, 1].

Return value

Numeric from 0 to PI, in radians.

03 · PRACTICAL EXAMPLE

Commented example

#Include "Protheus.ch"

User Function EdAcos()
    Local nCosine := 0
    // Check the domain before calculating.
    If nCosine >= -1 .And. nCosine <= 1
        ConOut(cValToChar(ACos(nCosine)))
    EndIf
Return Nil

Expected result

Expected result approximately 1.5707963268 radians, equivalent to 90 degrees. Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.

BEST PRACTICES

Validate numeric type and domain. Clamp rounding drift at the boundaries only when the mathematical specification requires it.
Under review: editorial example neither compiled nor run in Protheus. Check includes, release, RDD and context before testing.