How to do it...

1. Open the console and create the folder chapter03/recipe02.
2. Navigate to the directory.
3. Create the tolerance.go file with the following content:

        package main

        import (
          "fmt"
          "math"
        )

        const da = 0.29999999999999998889776975374843459576368331909180
        const db = 0.3
 
        func main() {

          daStr := fmt.Sprintf("%.10f", da)
          dbStr := fmt.Sprintf("%.10f", db)
 
          fmt.Printf("Strings %s = %s equals: %v \n", daStr,
                     dbStr, dbStr == daStr)
          fmt.Printf("Number equals: %v \n", db == da)

          // As the precision of float representation
          // is limited. For the float comparison it is
          // better to use comparison with some tolerance.
          fmt.Printf("Number equals with TOLERANCE: %v \n", 
                     equals(da, db))

        }

        const TOLERANCE = 1e-8
        // Equals compares the floating-point numbers
        // with tolerance 1e-8
        func equals(numA, numB float64) bool {
          delta := math.Abs(numA - numB)
          if delta < TOLERANCE {
            return true
          }
          return false
        }

1. Execute the command go run tolerance.go in the Terminal.
2. You will see the following output:

1. Create the file big.go with the following content:

        package main

        import (
          "fmt"
          "math/big"
        )

        var da float64 = 0.299999992
        var db float64 = 0.299999991

        var prec uint = 32
        var prec2 uint = 16

        func main() {

          fmt.Printf("Comparing float64 with '==' equals: %v\n", da == db)

          daB := big.NewFloat(da).SetPrec(prec)
          dbB := big.NewFloat(db).SetPrec(prec)

          fmt.Printf("A: %v \n", daB)
          fmt.Printf("B: %v \n", dbB)
          fmt.Printf("Comparing big.Float with precision: %d : %v\n",
                     prec, daB.Cmp(dbB) == 0)

          daB = big.NewFloat(da).SetPrec(prec2)
          dbB = big.NewFloat(db).SetPrec(prec2)

          fmt.Printf("A: %v \n", daB)
          fmt.Printf("B: %v \n", dbB)
          fmt.Printf("Comparing big.Float with precision: %d : %v\n",
                     prec2, daB.Cmp(dbB) == 0)

        }

1. Execute the code by running go run big.go in the Terminal.
2. You will see the following output: