diff options
Diffstat (limited to 'func.go')
| -rw-r--r-- | func.go | 26 |
1 files changed, 26 insertions, 0 deletions
@@ -10,6 +10,8 @@ func parseFunction(fn string) func(Calculator) { switch fn { case "sin", "cos", "tan": return trig(fn) + case "asin", "acos", "atan": + return invTrig(fn) } return nil } @@ -39,6 +41,30 @@ func trig(fn string) func(Calculator) { } } +// invTrig returns a closure that performs the inverse trig function specified +// by fn. Panics if fn is not one of "asin", "acos" or "atan". +func invTrig(fn string) func(Calculator) { + return func(c Calculator) { + if len(c.stack) <= 0 { + return + } + v := &c.stack[len(c.stack)-1] + switch fn { + case "asin": + *v = math.Asin(*v) + case "acos": + *v = math.Acos(*v) + case "atan": + *v = math.Atan(*v) + default: + panic(fmt.Sprintf("invalid inverse trig function: '%s'", fn)) + } + if c.anglem == modeDeg { + *v = degrees(*v) + } + } +} + // radians converts degrees to radians. func radians(deg float64) float64 { return deg * math.Pi / 180.0 |