Created
December 11, 2012 07:19
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| // For large numbers of math.Pow(x,y) calls, it's worth special-casing y=2 | |
| // and squaring it yourself. | |
| package main | |
| import ( | |
| "flag" | |
| "fmt" | |
| "math" | |
| ) | |
| var use_math = flag.Bool("m", false, "") | |
| const limit = 1000 * 1000 * 100 | |
| func main() { | |
| flag.Parse() | |
| if *use_math { | |
| fmt.Println("using math.Pow") | |
| for i := 0; i < limit; i++ { | |
| math.Pow(float64(i), 2) | |
| } | |
| } else { | |
| fmt.Println("using multiplication") | |
| for i := 0; i < limit; i++ { | |
| _ = i * i | |
| } | |
| } | |
| } | |
| /* | |
| On a recent MacBook Pro: | |
| $ time go run pow.go | |
| using multiplication | |
| real 0m0.336s | |
| user 0m0.293s | |
| sys 0m0.034s | |
| $ time go run pow.go -m | |
| using math.Pow | |
| real 0m6.707s | |
| user 0m6.667s | |
| sys 0m0.030s | |
| On a 2005-vintage MacBookPro: | |
| $ time go run pow.go | |
| using multiplication | |
| real 0m0.638s | |
| user 0m0.507s | |
| sys 0m0.069s | |
| $ time go run pow.go -m | |
| using math.Pow | |
| real 0m13.098s | |
| user 0m12.949s | |
| sys 0m0.084s | |
| */ |
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