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

# QwtDoubleInterval(3)

## NAME

QwtDoubleInterval -

## SYNOPSIS

`#include <qwt_double_interval.h>`

### Public Types

enum **BorderMode** { **IncludeBorders** =  0, **ExcludeMinimum** =  1, **ExcludeMaximum** =  2, **ExcludeBorders** =  ExcludeMinimum \| ExcludeMaximum }\

### Public Member Functions

**QwtDoubleInterval** ()\
 **QwtDoubleInterval** (double **minValue**, double **maxValue**, int **borderFlags**=IncludeBorders)\
 int **borderFlags** () const \
 bool **contains** (double value) const \
 **QwtDoubleInterval** **extend** (double value) const \
 **QwtDoubleInterval** **intersect** (const **QwtDoubleInterval** &) const \
 bool **intersects** (const **QwtDoubleInterval** &) const \
 void **invalidate** ()\
 **QwtDoubleInterval** **inverted** () const \
 bool **isNull** () const \
 bool **isValid** () const \
 **QwtDoubleInterval** **limited** (double **minValue**, double **maxValue**) const \
 double **maxValue** () const \
 double **minValue** () const \
 **QwtDoubleInterval** **normalized** () const \
 int **operator!=** (const **QwtDoubleInterval** &) const \
 **QwtDoubleInterval** **operator&** (const **QwtDoubleInterval** &) const \
 **QwtDoubleInterval** & **operator&=** (const **QwtDoubleInterval** &)\
 int **operator==** (const **QwtDoubleInterval** &) const \
 **QwtDoubleInterval** **operator\|** (const **QwtDoubleInterval** &) const \
 **QwtDoubleInterval** **operator\|** (double) const \
 **QwtDoubleInterval** & **operator\|=** (const **QwtDoubleInterval** &)\
 **QwtDoubleInterval** & **operator\|=** (double)\
 void **setBorderFlags** (int)\
 void **setInterval** (double **minValue**, double **maxValue**, int **borderFlags**=IncludeBorders)\
 void **setMaxValue** (double)\
 void **setMinValue** (double)\
 **QwtDoubleInterval** **symmetrize** (double value) const \
 **QwtDoubleInterval** **unite** (const **QwtDoubleInterval** &) const \
 double **width** () const \

## Detailed Description

A class representing an interval.

The interval is represented by 2 doubles, the lower and the upper limit.

## Member Enumeration Documentation

### enum QwtDoubleInterval::BorderMode

Flag indicating if a border is included/excluded from an interval

- •

  IncludeBorders\
  \
    min/max values are inside the interval

- •

  ExcludeMinimum\
  \
    min value is not included in the interval

- •

  ExcludeMaximum\
  \
    max value is not included in the interval

- •

  ExcludeBorders\
  \
    min/max values are not included in the interval

**See also:**

setBorderMode(), testBorderMode()

## Constructor & Destructor Documentation

### QwtDoubleInterval::QwtDoubleInterval ()` [inline]`

Default Constructor. Creates an invalid interval \[0.0, -1.0\]

**See also:**

**setInterval()**, **isValid()**

### QwtDoubleInterval::QwtDoubleInterval (doubleminValue, doublemaxValue, intborderFlags = `IncludeBorders`)` [inline]`

Constructor

Build an interval with from min/max values

**Parameters:**

*minValue* Minimum value \
 *maxValue* Maximum value \
 *borderFlags* Include/Exclude borders

## Member Function Documentation

### int QwtDoubleInterval::borderFlags () const` [inline]`

**Returns:**

Border flags

**See also:**

**setBorderFlags()**

### bool QwtDoubleInterval::contains (doublevalue) const

Test if a value is inside an interval

**Parameters:**

*value* Value

**Returns:**

true, if value \>= **minValue()** && value \<= **maxValue()**

### QwtDoubleInterval QwtDoubleInterval::extend (doublevalue) const

Extend the interval

If value is below minValue, value becomes the lower limit. If value is above maxValue, value becomes the upper limit.

extend has no effect for invalid intervals

**Parameters:**

*value* Value

**See also:**

**isValid()**

### bool QwtDoubleInterval::intersects (const QwtDoubleInterval &other) const

Test if two intervals overlap

### void QwtDoubleInterval::invalidate ()` [inline]`

Invalidate the interval

The limits are set to interval \[0.0, -1.0\]

**See also:**

**isValid()**

### QwtDoubleInterval QwtDoubleInterval::inverted () const

Invert the limits of the interval

**Returns:**

Inverted interval

**See also:**

**normalized()**

### bool QwtDoubleInterval::isNull () const` [inline]`

**Returns:**

true, if **isValid()** && (**minValue()** \>= **maxValue()**)

### bool QwtDoubleInterval::isValid () const` [inline]`

A interval is valid when **minValue()** \<= **maxValue()**. In case of QwtDoubleInterval::ExcludeBorders it is true when **minValue()** \< **maxValue()**

### QwtDoubleInterval QwtDoubleInterval::limited (doublelowerBound, doubleupperBound) const

Limit the interval, keeping the border modes

**Parameters:**

*lowerBound* Lower limit \
 *upperBound* Upper limit

**Returns:**

Limited interval

### double QwtDoubleInterval::maxValue () const` [inline]`

**Returns:**

Upper limit of the interval

### double QwtDoubleInterval::minValue () const` [inline]`

**Returns:**

Lower limit of the interval

### QwtDoubleInterval QwtDoubleInterval::normalized () const

Normalize the limits of the interval. If **maxValue()** \< **minValue()** the limits will be inverted.

**Returns:**

Normalized interval

**See also:**

**isValid()**, **inverted()**

### QwtDoubleInterval QwtDoubleInterval::operator& (const QwtDoubleInterval &interval) const` [inline]`

Intersection of two intervals

**See also:**

**intersect()**

### QwtDoubleInterval QwtDoubleInterval::operator\| (const QwtDoubleInterval &interval) const` [inline]`

Union of two intervals

**See also:**

**unite()**

### QwtDoubleInterval QwtDoubleInterval::operator\| (doublevalue) const` [inline]`

Extend an interval

**See also:**

**extend()**

### void QwtDoubleInterval::setBorderFlags (intborderFlags)` [inline]`

Change the border flags

**Parameters:**

*borderFlags* Or'd BorderMode flags

**See also:**

**borderFlags()**

### void QwtDoubleInterval::setInterval (doubleminValue, doublemaxValue, intborderFlags = `IncludeBorders`)` [inline]`

Assign the limits of the interval

**Parameters:**

*minValue* Minimum value \
 *maxValue* Maximum value \
 *borderFlags* Include/Exclude borders

### void QwtDoubleInterval::setMaxValue (doublemaxValue)` [inline]`

Assign the upper limit of the interval

**Parameters:**

*maxValue* Maximum value

### void QwtDoubleInterval::setMinValue (doubleminValue)` [inline]`

Assign the lower limit of the interval

**Parameters:**

*minValue* Minimum value

### QwtDoubleInterval QwtDoubleInterval::symmetrize (doublevalue) const

Adjust the limit that is closer to value, so that value becomes the center of the interval.

**Parameters:**

*value* Center

**Returns:**

Interval with value as center

### double QwtDoubleInterval::width () const` [inline]`

Return the width of an interval The width of invalid intervals is 0.0, otherwise the result is **maxValue()** - **minValue()**.

**See also:**

**isValid()**

## Author

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