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 // Copyright ©2013 The gonum Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package unit import ( "errors" "fmt" "math" ) // Dimless represents a dimensionless constant type Dimless float64 const ( One Dimless = 1.0 ) // Unit converts the Dimless to a unit func (d Dimless) Unit() *Unit { return New(float64(d), Dimensions{}) } // Dimless allows Dimless to implement a Dimlesser interface func (d Dimless) Dimless() Dimless { return d } // From converts the unit to a dimless. Returns an error if there // is a mismatch in dimension func (d *Dimless) From(u *Unit) error { if !DimensionsMatch(u, One) { (*d) = Dimless(math.NaN()) return errors.New("Dimension mismatch") } (*d) = Dimless(u.Unit().Value()) return nil } func (d Dimless) Format(fs fmt.State, c rune) { switch c { case 'v': if fs.Flag('#') { fmt.Fprintf(fs, "%T(%v)", d, float64(d)) return } fallthrough case 'e', 'E', 'f', 'F', 'g', 'G': p, pOk := fs.Precision() w, wOk := fs.Width() switch { case pOk && wOk: fmt.Fprintf(fs, "%*.*"+string(c), w, p, float64(d)) case pOk: fmt.Fprintf(fs, "%.*"+string(c), p, float64(d)) case wOk: fmt.Fprintf(fs, "%*"+string(c), w, float64(d)) default: fmt.Fprintf(fs, "%"+string(c), float64(d)) } default: fmt.Fprintf(fs, "%%!%c(%T=%g)", c, d, float64(d)) return } }