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