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