.TH "QwtScaleEngine" 3 "Wed Jan 2 2019" "Version 6.1.4" "Qwt User's Guide" \" -*- nroff -*-
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.SH NAME
QwtScaleEngine \- Base class for scale engines\&.  

.SH SYNOPSIS
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.PP
.PP
\fC#include <qwt_scale_engine\&.h>\fP
.PP
Inherited by \fBQwtLinearScaleEngine\fP, and \fBQwtLogScaleEngine\fP\&.
.SS "Public Types"

.in +1c
.ti -1c
.RI "enum \fBAttribute\fP { \fBNoAttribute\fP = 0x00, \fBIncludeReference\fP = 0x01, \fBSymmetric\fP = 0x02, \fBFloating\fP = 0x04, \fBInverted\fP = 0x08 }"
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.RI "typedef QFlags< \fBAttribute\fP > \fBAttributes\fP"
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.RI "Layout attributes\&. "
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.SS "Public Member Functions"

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.RI "\fBQwtScaleEngine\fP (uint \fBbase\fP=10)"
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.RI "virtual \fB~QwtScaleEngine\fP ()"
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.RI "Destructor\&. "
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.RI "void \fBsetBase\fP (uint \fBbase\fP)"
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.RI "uint \fBbase\fP () const"
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.RI "void \fBsetAttribute\fP (\fBAttribute\fP, bool on=true)"
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.RI "bool \fBtestAttribute\fP (\fBAttribute\fP) const"
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.RI "void \fBsetAttributes\fP (\fBAttributes\fP)"
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.RI "\fBAttributes\fP \fBattributes\fP () const"
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.RI "void \fBsetReference\fP (double)"
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.RI "Specify a reference point\&. "
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.RI "double \fBreference\fP () const"
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.RI "void \fBsetMargins\fP (double lower, double upper)"
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.RI "Specify margins at the scale's endpoints\&. "
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.RI "double \fBlowerMargin\fP () const"
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.RI "double \fBupperMargin\fP () const"
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.RI "virtual void \fBautoScale\fP (int maxNumSteps, double &x1, double &x2, double &stepSize) const =0"
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.RI "virtual \fBQwtScaleDiv\fP \fBdivideScale\fP (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0\&.0) const =0"
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.RI "Calculate a scale division\&. "
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.RI "void \fBsetTransformation\fP (\fBQwtTransform\fP *)"
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.RI "\fBQwtTransform\fP * \fBtransformation\fP () const"
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.SS "Protected Member Functions"

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.RI "bool \fBcontains\fP (const \fBQwtInterval\fP &, double value) const"
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.RI "QList< double > \fBstrip\fP (const QList< double > &, const \fBQwtInterval\fP &) const"
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.RI "double \fBdivideInterval\fP (double intervalSize, int numSteps) const"
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.RI "\fBQwtInterval\fP \fBbuildInterval\fP (double value) const"
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.RI "Build an interval around a value\&. "
.in -1c
.SH "Detailed Description"
.PP 
Base class for scale engines\&. 

A scale engine tries to find 'reasonable' ranges and step sizes for scales\&.
.PP
The layout of the scale can be varied with \fBsetAttribute()\fP\&.
.PP
Qwt offers implementations for logarithmic and linear scales\&. 
.SH "Member Enumeration Documentation"
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.SS "enum \fBQwtScaleEngine::Attribute\fP"
Layout attributes 
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\fBSee also:\fP
.RS 4
\fBsetAttribute()\fP, \fBtestAttribute()\fP, \fBreference()\fP, \fBlowerMargin()\fP, \fBupperMargin()\fP 
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.PP
\fBEnumerator\fP
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.TP
\fB\fINoAttribute \fP\fP
No attributes\&. 
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\fB\fIIncludeReference \fP\fP
Build a scale which includes the \fBreference()\fP value\&. 
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\fB\fISymmetric \fP\fP
Build a scale which is symmetric to the \fBreference()\fP value\&. 
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\fB\fIFloating \fP\fP
The endpoints of the scale are supposed to be equal the outmost included values plus the specified margins (see \fBsetMargins()\fP)\&. If this attribute is \fInot\fP set, the endpoints of the scale will be integer multiples of the step size\&. 
.TP
\fB\fIInverted \fP\fP
Turn the scale upside down\&. 
.SH "Constructor & Destructor Documentation"
.PP 
.SS "QwtScaleEngine::QwtScaleEngine (uint base = \fC10\fP)\fC [explicit]\fP"
Constructor
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\fBParameters:\fP
.RS 4
\fIbase\fP Base of the scale engine 
.RE
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\fBSee also:\fP
.RS 4
\fBsetBase()\fP 
.RE
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.SH "Member Function Documentation"
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.SS "\fBQwtScaleEngine::Attributes\fP QwtScaleEngine::attributes () const"

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\fBReturns:\fP
.RS 4
Scale attributes 
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\fBSee also:\fP
.RS 4
\fBAttribute\fP, \fBsetAttributes()\fP, \fBtestAttribute()\fP 
.RE
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.SS "virtual void QwtScaleEngine::autoScale (int maxNumSteps, double & x1, double & x2, double & stepSize) const\fC [pure virtual]\fP"
Align and divide an interval
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\fBParameters:\fP
.RS 4
\fImaxNumSteps\fP Max\&. number of steps 
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\fIx1\fP First limit of the interval (In/Out) 
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\fIx2\fP Second limit of the interval (In/Out) 
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\fIstepSize\fP Step size (Return value) 
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.PP
Implemented in \fBQwtLogScaleEngine\fP, \fBQwtLinearScaleEngine\fP, and \fBQwtDateScaleEngine\fP\&.
.SS "uint QwtScaleEngine::base () const"

.PP
\fBReturns:\fP
.RS 4
base Base of the scale engine 
.RE
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\fBSee also:\fP
.RS 4
\fBsetBase()\fP 
.RE
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.SS "\fBQwtInterval\fP QwtScaleEngine::buildInterval (double value) const\fC [protected]\fP"

.PP
Build an interval around a value\&. In case of v == 0\&.0 the interval is [-0\&.5, 0\&.5], otherwide it is [0\&.5 * v, 1\&.5 * v]
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\fBParameters:\fP
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\fIvalue\fP Initial value 
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\fBReturns:\fP
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Calculated interval 
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.SS "bool QwtScaleEngine::contains (const \fBQwtInterval\fP & interval, double value) const\fC [protected]\fP"
Check if an interval 'contains' a value
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\fBParameters:\fP
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\fIinterval\fP Interval 
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\fIvalue\fP Value
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\fBReturns:\fP
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True, when the value is inside the interval 
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.SS "double QwtScaleEngine::divideInterval (double intervalSize, int numSteps) const\fC [protected]\fP"
Calculate a step size for an interval size
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\fBParameters:\fP
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\fIintervalSize\fP Interval size 
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\fInumSteps\fP Number of steps
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\fBReturns:\fP
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Step size 
.RE
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.SS "virtual \fBQwtScaleDiv\fP QwtScaleEngine::divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize = \fC0\&.0\fP) const\fC [pure virtual]\fP"

.PP
Calculate a scale division\&. 
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\fBParameters:\fP
.RS 4
\fIx1\fP First interval limit 
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\fIx2\fP Second interval limit 
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\fImaxMajorSteps\fP Maximum for the number of major steps 
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\fImaxMinorSteps\fP Maximum number of minor steps 
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\fIstepSize\fP Step size\&. If stepSize == 0\&.0, the scaleEngine calculates one\&.
.RE
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\fBReturns:\fP
.RS 4
Calculated scale division 
.RE
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.PP
Implemented in \fBQwtLogScaleEngine\fP, \fBQwtLinearScaleEngine\fP, and \fBQwtDateScaleEngine\fP\&.
.SS "double QwtScaleEngine::lowerMargin () const"

.PP
\fBReturns:\fP
.RS 4
the margin at the lower end of the scale The default margin is 0\&.
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\fBSee also:\fP
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\fBsetMargins()\fP 
.RE
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.SS "double QwtScaleEngine::reference () const"

.PP
\fBReturns:\fP
.RS 4
the reference value 
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\fBSee also:\fP
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\fBsetReference()\fP, \fBsetAttribute()\fP 
.RE
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.SS "void QwtScaleEngine::setAttribute (\fBAttribute\fP attribute, bool on = \fCtrue\fP)"
Change a scale attribute
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\fBParameters:\fP
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\fIattribute\fP Attribute to change 
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\fIon\fP On/Off
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\fBSee also:\fP
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\fBAttribute\fP, \fBtestAttribute()\fP 
.RE
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.SS "void QwtScaleEngine::setAttributes (\fBAttributes\fP attributes)"
Change the scale attribute
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\fBParameters:\fP
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\fIattributes\fP Set scale attributes 
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\fBSee also:\fP
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\fBAttribute\fP, \fBattributes()\fP 
.RE
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.SS "void QwtScaleEngine::setBase (uint base)"
Set the base of the scale engine
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While a base of 10 is what 99\&.9% of all applications need certain scales might need a different base: f\&.e 2
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The default setting is 10
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\fBParameters:\fP
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\fIbase\fP Base of the engine
.RE
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\fBSee also:\fP
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\fBbase()\fP 
.RE
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.SS "void QwtScaleEngine::setMargins (double lower, double upper)"

.PP
Specify margins at the scale's endpoints\&. 
.PP
\fBParameters:\fP
.RS 4
\fIlower\fP minimum distance between the scale's lower boundary and the smallest enclosed value 
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\fIupper\fP minimum distance between the scale's upper boundary and the greatest enclosed value
.RE
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Margins can be used to leave a minimum amount of space between the enclosed intervals and the boundaries of the scale\&.
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\fBWarning:\fP
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.PD 0
.IP "\(bu" 2
\fBQwtLogScaleEngine\fP measures the margins in decades\&.
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.RE
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\fBSee also:\fP
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\fBupperMargin()\fP, \fBlowerMargin()\fP 
.RE
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.SS "void QwtScaleEngine::setReference (double reference)"

.PP
Specify a reference point\&. 
.PP
\fBParameters:\fP
.RS 4
\fIreference\fP New reference value
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The reference point is needed if options IncludeReference or Symmetric are active\&. Its default value is 0\&.0\&.
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\fBSee also:\fP
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\fBAttribute\fP 
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.SS "void QwtScaleEngine::setTransformation (\fBQwtTransform\fP * transform)"
Assign a transformation
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\fBParameters:\fP
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\fItransform\fP Transformation
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The transformation object is used as factory for clones that are returned by \fBtransformation()\fP
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The scale engine takes ownership of the transformation\&.
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\fBSee also:\fP
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\fBQwtTransform::copy()\fP, \fBtransformation()\fP 
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.SS "QList< double > QwtScaleEngine::strip (const QList< double > & ticks, const \fBQwtInterval\fP & interval) const\fC [protected]\fP"
Remove ticks from a list, that are not inside an interval
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\fBParameters:\fP
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\fIticks\fP Tick list 
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\fIinterval\fP Interval
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\fBReturns:\fP
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Stripped tick list 
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.SS "bool QwtScaleEngine::testAttribute (\fBAttribute\fP attribute) const"

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\fBReturns:\fP
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True, if attribute is enabled\&.
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\fBParameters:\fP
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\fIattribute\fP Attribute to be tested 
.RE
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\fBSee also:\fP
.RS 4
\fBAttribute\fP, \fBsetAttribute()\fP 
.RE
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.SS "\fBQwtTransform\fP * QwtScaleEngine::transformation () const"
Create and return a clone of the transformation of the engine\&. When the engine has no special transformation NULL is returned, indicating no transformation\&.
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\fBReturns:\fP
.RS 4
A clone of the transfomation 
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\fBSee also:\fP
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\fBsetTransformation()\fP 
.RE
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.SS "double QwtScaleEngine::upperMargin () const"

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\fBReturns:\fP
.RS 4
the margin at the upper end of the scale The default margin is 0\&.
.RE
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\fBSee also:\fP
.RS 4
\fBsetMargins()\fP 
.RE
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.SH "Author"
.PP 
Generated automatically by Doxygen for Qwt User's Guide from the source code\&.