lsst::geom::polynomials::Scaling1d Class Reference

A 1-d affine transform that can be used to map one interval to another. More...

#include <Scaling1d.h>

Public Member Functions
	Scaling1d (double scale, double shift) noexcept
	Construct from the given multiplicative scale and additive shift.
	Scaling1d (Scaling1d const &) noexcept=default
	Default copy constructor.
	Scaling1d (Scaling1d &&) noexcept=default
	Default move constructor.
Scaling1d &	operator= (Scaling1d const &) noexcept=default
	Default copy assignment.
Scaling1d &	operator= (Scaling1d &&) noexcept=default
	Default move assignment.
double	applyForward (double x) const noexcept
	Apply the transform in the forward direction.
double	applyInverse (double y) const noexcept
	Apply the inverse of the forward transform;.
double	getScale () const noexcept
	Return the multiplicative scaling.
double	getShift () const noexcept
	Return the additive shift.
Scaling1d	inverted () const noexcept
	Invert the transform.
Scaling1d	then (Scaling1d const &second) const noexcept
	Compose two transforms.

Detailed Description

A 1-d affine transform that can be used to map one interval to another.

The transform is represented as an additive shift followed by a multiplicative scaling.

Note

This class (and especially its 2-d counterpart, Scaling2d) has a lot in common with geom::AffineTransform, and ideally they should share code and be highly interoperable. Doing that well would require a larger-scale rethink of geom, however, and at present we don't actually have a use case for that interoperability, so it's something we should keep in mind for the future, not a high priority for the present.

Exception Safety

All operations on Scaling1d are noexcept.

See also

makeUnitRangeScaling1d

Definition at line 46 of file Scaling1d.h.

Constructor & Destructor Documentation

Scaling1d() [1/3]

lsst::geom::polynomials::Scaling1d::Scaling1d ( double scale, double shift )

inlinenoexcept

Construct from the given multiplicative scale and additive shift.

Definition at line 50 of file Scaling1d.h.

                                                  :
        _scale(scale),
        _shift(shift)
    {}

Scaling1d() [2/3]

lsst::geom::polynomials::Scaling1d::Scaling1d ( Scaling1d const & )

defaultnoexcept

Default copy constructor.

Scaling1d() [3/3]

lsst::geom::polynomials::Scaling1d::Scaling1d ( Scaling1d && )

defaultnoexcept

Default move constructor.

Member Function Documentation

applyForward()

double lsst::geom::polynomials::Scaling1d::applyForward ( double x ) const

inlinenoexcept

Apply the transform in the forward direction.

Result is defined to be (x + getShift()) * getScale().

Definition at line 72 of file Scaling1d.h.

                                                 {
        return (x + getShift())*getScale();
    }

applyInverse()

double lsst::geom::polynomials::Scaling1d::applyInverse ( double y ) const

inlinenoexcept

Apply the inverse of the forward transform;.

Definition at line 79 of file Scaling1d.h.

                                                 {
        return y/_scale - _shift;
    }

getScale()

double lsst::geom::polynomials::Scaling1d::getScale ( ) const

inlinenoexcept

Return the multiplicative scaling.

Definition at line 84 of file Scaling1d.h.

{ return _scale; }

getShift()

double lsst::geom::polynomials::Scaling1d::getShift ( ) const

inlinenoexcept

Return the additive shift.

Definition at line 87 of file Scaling1d.h.

{ return _shift; }

inverted()

Scaling1d lsst::geom::polynomials::Scaling1d::inverted ( ) const

inlinenoexcept

Invert the transform.

If r = t.inverted(), then r.applyForward(x) is equivalent to t.applyInverse(x) and r.applyInverse(y) is equivalent to t.applyForward(y).

Definition at line 96 of file Scaling1d.h.

                                        {
        return Scaling1d(1.0/_scale, -_shift*_scale);
    }

operator=() [1/2]

Scaling1d & lsst::geom::polynomials::Scaling1d::operator= ( Scaling1d && )

defaultnoexcept

Default move assignment.

operator=() [2/2]

Scaling1d & lsst::geom::polynomials::Scaling1d::operator= ( Scaling1d const & )

defaultnoexcept

Default copy assignment.

then()

Scaling1d lsst::geom::polynomials::Scaling1d::then ( Scaling1d const & second ) const

inlinenoexcept

Compose two transforms.

If r = a.then(b), then r.applyForward(x) is equivalent to b.applyForward(a.applyForward(x)) and r.applyInverse(y) is equivalent to a.applyInverse(b.applyInverse(y)).

Definition at line 107 of file Scaling1d.h.

                                                            {
        return Scaling1d(getScale()*second.getScale(),
                                 getShift() + second.getShift()/getScale());
    }

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The documentation for this class was generated from the following file:

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-12.0.0/Linux/geom/g90f42f885a+e1755607f3/include/lsst/geom/polynomials/Scaling1d.h