---
name: "QwtLog10ScaleEngine"
section: "3"
platform: "linux"
package: "libqwt5-doc"
version: "5.2.3-1"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/QwtLog10ScaleEngine"
---

# QwtLog10ScaleEngine(3)

## NAME

QwtLog10ScaleEngine -

## SYNOPSIS

`#include <qwt_scale_engine.h>`

Inherits **QwtScaleEngine**.

### Public Member Functions

virtual void **autoScale** (int maxSteps, double &x1, double &x2, double &stepSize) const \
 virtual **QwtScaleDiv** **divideScale** (double x1, double x2, int numMajorSteps, int numMinorSteps, double stepSize=0.0) const \
 virtual **QwtScaleTransformation** \* **transformation** () const \

### Protected Member Functions

**QwtDoubleInterval** **log10** (const **QwtDoubleInterval** &) const \
 **QwtDoubleInterval** **pow10** (const **QwtDoubleInterval** &) const \

### Additional Inherited Members

## Detailed Description

A scale engine for logarithmic (base 10) scales.

The step size is measured in *decades* and the major step size will be adjusted to fit the pattern $re n is a natural number including zero.

**Warning:**

the step size as well as the margins are measured in *decades*.

## Member Function Documentation

### void QwtLog10ScaleEngine::autoScale (intmaxNumSteps, double &x1, double &x2, double &stepSize) const` [virtual]`

Align and divide an interval

**Parameters:**

*maxNumSteps* Max. number of steps \
 *x1* First limit of the interval (In/Out) \
 *x2* Second limit of the interval (In/Out) \
 *stepSize* Step size (Out)

**See also:**

**QwtScaleEngine::setAttribute()**

Implements **QwtScaleEngine**.

### QwtScaleDiv QwtLog10ScaleEngine::divideScale (doublex1, doublex2, intmaxMajSteps, intmaxMinSteps, doublestepSize = `0.0`) const` [virtual]`

Calculate a scale division. **Parameters:**

*x1* First interval limit \
 *x2* Second interval limit \
 *maxMajSteps* Maximum for the number of major steps \
 *maxMinSteps* Maximum number of minor steps \
 *stepSize* Step size. If stepSize == 0, the scaleEngine calculates one.

**See also:**

QwtScaleEngine::stepSize(), QwtLog10ScaleEngine::subDivide()

Implements **QwtScaleEngine**.

### QwtDoubleInterval QwtLog10ScaleEngine::log10 (const QwtDoubleInterval &interval) const` [protected]`

Return the interval \[log10(interval.minValue(), log10(interval.maxValue\]

### QwtDoubleInterval QwtLog10ScaleEngine::pow10 (const QwtDoubleInterval &interval) const` [protected]`

Return the interval \[pow10(interval.minValue(), pow10(interval.maxValue\]

### QwtScaleTransformation \* QwtLog10ScaleEngine::transformation () const` [virtual]`

Return a transformation, for logarithmic (base 10) scales

Implements **QwtScaleEngine**.

## Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.