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java.lang.Object uk.ac.starlink.ast.Mapping.Interpolator
public static class Mapping.Interpolator
Controls the interpolation scheme used by Mapping
's
resampling methods. This class has no public constructors, but
provides static factory methods which generate Interpolator
objects that can be passed to the resample*
methods.
There are a number of standard schemes, and users may supply their
own by implementing the Ukern1Calculator
or
UinterpCalculator
interfaces.
Method Summary  

static Mapping.Interpolator 
blockAve(int npix)
Returns a block averaging resampling interpolator. 
static Mapping.Interpolator 
linear()
Returns a resampling interpolator which does linear interpolation. 
static Mapping.Interpolator 
nearest()
Returns a resampling interpolator which does nearestneighbour 'interpolation'. 
static Mapping.Interpolator 
sinc(int npix)
Returns a resampling interpolator which uses a sinc(pi*x) 1dimensional kernel. 
static Mapping.Interpolator 
sincCos(int npix,
double width)
Returns a resampling interpolator which uses a sinc(pi*x).cos(k*pi*x) 1dimensional kernel. 
static Mapping.Interpolator 
sincGauss(int npix,
double fwhm)
Returns a resampling interpolator which uses a sinc(pi*x).exp(k*x*x) 1dimensional kernel. 
static Mapping.Interpolator 
sincSinc(int npix,
double width)
Returns a resampling interpolator which uses a sinc(pi*x).sinc(k*pi*x) 1dimensional kernel. 
static Mapping.Interpolator 
somb(int npix)
Returns a resampling interpolator which uses a somb(pi*x) 1dimensional kernel
(a "sombrero" function). 
static Mapping.Interpolator 
sombCos(int npix,
double width)
Returns a resampling interpolator which uses a somb(pi*x).cos(k*pi*x) 1dimensional kernel. 
static Mapping.Interpolator 
uinterp(UinterpCalculator uinterper)
Returns a resampling interpolator which uses a given userdefined generic resampling function. 
static Mapping.Interpolator 
ukern1(Ukern1Calculator ukern1er,
int npix)
Returns a resampling interpolator which uses a given userdefined 1dimensional kernel. 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Method Detail 

public static Mapping.Interpolator nearest()
public static Mapping.Interpolator linear()
public static Mapping.Interpolator sinc(int npix)
sinc(pi*x)
1dimensional kernel.
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.
public static Mapping.Interpolator sincSinc(int npix, double width)
sinc(pi*x).sinc(k*pi*x)
1dimensional kernel.
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.width
 the number of pixels at which the envelope goes
to zero. Should be at least 1.0.
public static Mapping.Interpolator sincCos(int npix, double width)
sinc(pi*x).cos(k*pi*x)
1dimensional kernel.
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.width
 the number of pixels at which the envelope goes
to zero. Should be at least 1.0.
public static Mapping.Interpolator somb(int npix)
somb(pi*x)
1dimensional kernel
(a "sombrero" function).
x
is the pixel offset from the interpolation point
and somb(z)=2*1(z)/z
(J1 is a Bessel function
of the first kind of order 1).
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.
public static Mapping.Interpolator sombCos(int npix, double width)
somb(pi*x).cos(k*pi*x)
1dimensional kernel.
k
is a constant, out to the point where
cos(k*pi*x) goes to zero, and zero beyond,
and somb(z)=2*1(z)/z
(J1 is a Bessel function
of the first kind of order 1).
 Parameters:
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.width
 the number of pixels at which the envelope goes
to zero. Should be at least 1.0.
 Returns:
 a sinccostype resampling Interpolator
sincGauss
public static Mapping.Interpolator sincGauss(int npix,
double fwhm)
 Returns a resampling interpolator which uses a
sinc(pi*x).exp(k*x*x)
1dimensional kernel.
 Parameters:
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.fwhm
 the full width at half maximum of the Gaussian
envelope. Should be at least 0.1.
 Returns:
 a sincGausstype resampling Interpolator
blockAve
public static Mapping.Interpolator blockAve(int npix)
 Returns a block averaging resampling interpolator.
 Parameters:
npix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
 Returns:
 a block averaging resampling Interpolator
ukern1
public static Mapping.Interpolator ukern1(Ukern1Calculator ukern1er,
int npix)
 Returns a resampling interpolator which uses a given userdefined
1dimensional kernel.
 Parameters:
ukern1er
 a Ukern1Calculator object which defines a
1dimensional kernel functionnpix
 the number of pixels to contribute to the
interpolated result on either side of the
interpolation point in each dimension.
Execution time increases rapidly with this number.
Typically, a value of 2 is appropriate and the
minimum value used will be 1. A value of zero
or less may be given to indicate that a suitable
number of pixels should be calculated automatically.
 Returns:
 a user 1d kernel resampling Interpolator
uinterp
public static Mapping.Interpolator uinterp(UinterpCalculator uinterper)
 Returns a resampling interpolator which uses a given userdefined
generic resampling function.
 Parameters:
uinterper
 a UinterpCalculator object which defines a generic
resampling function
 Returns:
 a generic userdefined resampling Interpolator
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