diff options
Diffstat (limited to 'calc.go')
| -rw-r--r-- | calc.go | 60 |
1 files changed, 60 insertions, 0 deletions
@@ -227,6 +227,8 @@ var tokenPriority = map[string]int{ // AVERAGE // AVERAGEA // BASE +// BESSELI +// BESSELJ // BIN2DEC // BIN2HEX // BIN2OCT @@ -1226,6 +1228,64 @@ func formulaCriteriaEval(val string, criteria *formulaCriteria) (result bool, er // Engineering Functions +// BESSELI function the modified Bessel function, which is equivalent to the +// Bessel function evaluated for purely imaginary arguments. The syntax of +// the Besseli function is: +// +// BESSELI(x,n) +// +func (fn *formulaFuncs) BESSELI(argsList *list.List) formulaArg { + if argsList.Len() != 2 { + return newErrorFormulaArg(formulaErrorVALUE, "BESSELI requires 2 numeric arguments") + } + return fn.bassel(argsList, true) +} + +// BESSELJ function returns the Bessel function, Jn(x), for a specified order +// and value of x. The syntax of the function is: +// +// BESSELJ(x,n) +// +func (fn *formulaFuncs) BESSELJ(argsList *list.List) formulaArg { + if argsList.Len() != 2 { + return newErrorFormulaArg(formulaErrorVALUE, "BESSELJ requires 2 numeric arguments") + } + return fn.bassel(argsList, false) +} + +// bassel is an implementation of the formula function BESSELI and BESSELJ. +func (fn *formulaFuncs) bassel(argsList *list.List, modfied bool) formulaArg { + x, n := argsList.Front().Value.(formulaArg).ToNumber(), argsList.Back().Value.(formulaArg).ToNumber() + if x.Type != ArgNumber { + return x + } + if n.Type != ArgNumber { + return n + } + max, x1 := 100, x.Number*0.5 + x2 := x1 * x1 + x1 = math.Pow(x1, n.Number) + n1, n2, n3, n4, add := fact(n.Number), 1.0, 0.0, n.Number, false + result := x1 / n1 + t := result * 0.9 + for result != t && max != 0 { + x1 *= x2 + n3++ + n1 *= n3 + n4++ + n2 *= n4 + t = result + if modfied || add { + result += (x1 / n1 / n2) + } else { + result -= (x1 / n1 / n2) + } + max-- + add = !add + } + return newNumberFormulaArg(result) +} + // BIN2DEC function converts a Binary (a base-2 number) into a decimal number. // The syntax of the function is: // |