# QwtScaleTransformation Class Reference

List of all members.

## Detailed Description

Operations for linear or logarithmic (base 10) transformations.

Definition at line 19 of file qwt_scale_map.h.

## Public Types

enum | Type { Linear, Log10, Other }

## Public Member Functions

| QwtScaleTransformation (Type type)
virtual | ~QwtScaleTransformation ()
virtual double | xForm (double x, double s1, double s2, double p1, double p2) const
virtual double | invXForm (double x, double s1, double s2, double p1, double p2) const
Type | type () const
virtual QwtScaleTransformation * | copy () const

## Constructor & Destructor Documentation

QwtScaleTransformation::QwtScaleTransformation | ( | Type | type | ) |

| Constructor for a linear transformation. Definition at line 16 of file qwt_scale_map.cpp. References QwtScaleTransformation(). Referenced by QwtScaleTransformation().

## Member Function Documentation

double QwtScaleTransformation::invXForm | ( | double | p,
|  | double | p1,
|  | double | p2,
|  | double | s1,
|  | double | s2
| ) | const`[virtual]`

Transform a value from a linear to a logarithmic interval.

Parameters:

  | x | value related to the linear interval [p1, p2]
  | p1 | first border of linear interval
  | p2 | first border of linear interval
  | s1 | first border of logarithmic interval
  | s2 | first border of logarithmic interval

Returns:
  exp((x - p1) / (p2 - p1) * log(s2 / s1)) * s1;

Definition at line 70 of file qwt_scale_map.cpp.

Referenced by QwtScaleMap::invTransform().

double QwtScaleTransformation::xForm | ( | double | s,
|  | double | s1,
|  | double | s2,
|  | double | p1,
|  | double | p2
| ) | const`[virtual]`

Transform a value between 2 linear intervals.

Parameters:

  | x | value related to the interval [x1, x2]
  | x1 | first border of source interval
  | x2 | first border of source interval
  | y1 | first border of target interval
  | y2 | first border of target interval

Returns:
  linear mapping:
    y1 + (y2 - y1) / (x2 - x1) * (x - x1)
  log10 mapping:
    p1 + (p2 - p1) / log(s2 / s1) * log(x / s1)

Definition at line 47 of file qwt_scale_map.cpp.

Referenced by QwtScaleMap::xTransform().