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45 lines
1.0 KiB
Go
Executable File
45 lines
1.0 KiB
Go
Executable File
// Concurrent computation of pi.
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// See http://goo.gl/ZuTZM. - Comparison with Scala!
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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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"time"
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)
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func main() {
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start := time.Now()
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fmt.Println(CalculatePi(5000))
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end := time.Now()
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delta := end.Sub(start)
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fmt.Printf("longCalculation took this amount of time: %s\n", delta)
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}
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// CalculatePi launches n goroutines to compute an
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// series-approximation of pi.
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func CalculatePi(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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// calculate k-th term in the series
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go term(ch, float64(k))
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}
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f := 0.0
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//wait for all goroutines to complete, get and sum up their results:
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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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/* Output:
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3.14179261359579
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The calculation took this amount of time: 0.028002
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*/ |