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float.go
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float.go
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// seehuhn.de/go/pdf - a library for reading and writing PDF files
// Copyright (C) 2022 Jochen Voss <voss@seehuhn.de>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package float
import (
"regexp"
"strconv"
"strings"
)
func Format(x float64, precision int) string {
out := strconv.FormatFloat(x, 'f', precision, 64)
if m := tailRegexp.FindStringSubmatchIndex(out); m != nil {
if m[2] > 0 {
out = out[:m[2]]
} else if m[4] > 0 {
out = out[:m[4]]
}
}
if strings.HasPrefix(out, "0.") {
out = out[1:]
}
return out
}
func Round(x float64, digits int) float64 {
s := Format(x, digits)
y, err := strconv.ParseFloat(s, 64)
if err != nil {
panic(err)
}
return y
}
var (
tailRegexp = regexp.MustCompile(`(?:\..*[1-9](0+)|(\.0+))$`)
)