// Concurrent computation of pi.
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// See https://goo.gl/la6Kli.
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//
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// This demonstrates Go's ability to handle
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// large numbers of concurrent processes.
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// It is an unreasonable way to calculate pi.
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package main
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import (
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"fmt"
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"math"
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)
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func main() {
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fmt.Println(pi(5000))
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}
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// pi launches n goroutines to compute an
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// approximation of pi.
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func pi(n int) float64 {
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ch := make(chan float64)
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for k := 0; k <= n; k++ {
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go term(ch, float64(k))
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}
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f := 0.0
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for k := 0; k <= n; k++ {
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f += <-ch
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}
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return f
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}
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func term(ch chan float64, k float64) {
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ch <- 4 * math.Pow(-1, k) / (2*k + 1)
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}
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