| // 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 |
| } |
| } |