uk.ac.starlink.ast
Class Interval

java.lang.Object
  extended by uk.ac.starlink.ast.AstObject
      extended by uk.ac.starlink.ast.Mapping
          extended by uk.ac.starlink.ast.Frame
              extended by uk.ac.starlink.ast.Region
                  extended by uk.ac.starlink.ast.Interval

public class Interval
extends Region

Java interface to the AST Interval class - a region representing an interval on one or more axes of a Frame. The Interval class implements a Region which represents upper and/or lower limits on one or more axes of a Frame. For a point to be within the region represented by the Interval, the point must satisfy all the restrictions placed on all the axes. The point is outside the region if it fails to satisfy any one of the restrictions. Each axis may have either an upper limit, a lower limit, both or neither. If both limits are supplied but are in reverse order (so that the lower limit is greater than the upper limit), then the interval is an excluded interval, rather than an included interval.

Note, The Interval class makes no allowances for cyclic nature of some coordinate systems (such as SkyFrame coordinates). A Box should usually be used in these cases since this requires the user to think about suitable upper and lower limits,

Licence

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public Licence as published by the Free Software Foundation; either version 2 of the Licence, or (at your option) any later version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public Licence for more details.

You should have received a copy of the GNU General Public Licence along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street,Fifth Floor, Boston, MA 02110-1301, USA

See Also:
AST Interval

Nested Class Summary
 
Nested classes/interfaces inherited from class uk.ac.starlink.ast.Mapping
Mapping.Interpolator, Mapping.Spreader
 
Field Summary
 
Fields inherited from class uk.ac.starlink.ast.Region
OVERLAP_INSIDE, OVERLAP_NEGATE, OVERLAP_NONE, OVERLAP_OUTSIDE, OVERLAP_PARTIAL, OVERLAP_SAME, OVERLAP_UNKNOWN
 
Fields inherited from class uk.ac.starlink.ast.Mapping
LINEAR_INTERPOLATOR, LINEAR_SPREADER, NEAREST_INTERPOLATOR, NEAREST_SPREADER
 
Fields inherited from class uk.ac.starlink.ast.AstObject
AST__BAD, AST__TUNULL, pointer
 
Constructor Summary
Interval(Frame frame, double[] lbnd, double[] ubnd, Region unc)
          Create a Interval.
 
Method Summary
 
Methods inherited from class uk.ac.starlink.ast.Region
getAdaptive, getBounded, getClosed, getFillFactor, getMeshSize, getNegated, getRegionBounds, getRegionFrame, getRegionPoints, getUnc, mapRegion, mask, maskB, maskD, maskF, maskI, maskL, maskS, negate, overlap, setAdaptive, setClosed, setFillFactor, setMeshSize, setNegated, setUnc, showMesh
 
Methods inherited from class uk.ac.starlink.ast.Frame
angle, axAngle, axDistance, axOffset, convert, distance, findFrame, format, getActiveUnit, getAlignSystem, getBottom, getDigits, getDigits, getDirection, getDomain, getDut1, getEpoch, getFormat, getLabel, getMatchEnd, getMaxAxes, getMinAxes, getNaxes, getNormUnit, getObsLat, getObsLon, getPermute, getPreserveAxes, getSymbol, getSystem, getTitle, getTop, getUnit, intersect, norm, offset, offset2, permAxes, pickAxes, resolve, setActiveUnit, setAlignSystem, setBottom, setDigits, setDigits, setDirection, setDomain, setDut1, setEpoch, setEpoch, setFormat, setLabel, setMatchEnd, setMaxAxes, setMinAxes, setObsLat, setObsLon, setPermute, setPreserveAxes, setSymbol, setSystem, setTitle, setTop, setUnit, unformat
 
Methods inherited from class uk.ac.starlink.ast.Mapping
decompose, getInvert, getNin, getNout, getReport, getTranForward, getTranInverse, invert, linearApprox, mapBox, mapSplit, rate, rebin, rebinD, rebinF, rebinI, resample, resampleB, resampleD, resampleF, resampleI, resampleL, resampleS, setInvert, setReport, simplify, tran1, tran2, tranGrid, tranN, tranP
 
Methods inherited from class uk.ac.starlink.ast.AstObject
annul, clear, copy, delete, equals, finalize, getAstConstantI, getB, getC, getD, getF, getI, getID, getIdent, getL, getNobject, getObjSize, getRefCount, hashCode, isThreaded, reportVersions, sameObject, set, setB, setC, setD, setF, setI, setID, setIdent, setL, show, test, tune
 
Methods inherited from class java.lang.Object
clone, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Interval

public Interval(Frame frame,
                double[] lbnd,
                double[] ubnd,
                Region unc)
Create a Interval. This function creates a new Interval and optionally initialises its attributes.

A Interval is a Region which represents upper and/or lower limits on one or more axes of a Frame. For a point to be within the region represented by the Interval, the point must satisfy all the restrictions placed on all the axes. The point is outside the region if it fails to satisfy any one of the restrictions. Each axis may have either an upper limit, a lower limit, both or neither. If both limits are supplied but are in reverse order (so that the lower limit is greater than the upper limit), then the interval is an excluded interval, rather than an included interval.

At least one axis limit must be supplied.

Note, The Interval class makes no allowances for cyclic nature of some coordinate systems (such as SkyFrame coordinates). A Box should usually be used in these cases since this requires the user to think about suitable upper and lower limits,

Notes


- A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

Status Handling

The protected interface to this function includes an extra parameter at the end of the parameter list descirbed above. This parameter is a pointer to the integer inherited status variable: "int *status".

Parameters:
frame - A pointer to the Frame in which the region is defined. A deep copy is taken of the supplied Frame. This means that any subsequent changes made to the Frame using the supplied pointer will have no effect the Region.
lbnd - An array of double, with one element for each Frame axis (Naxes attribute) containing the lower limits on each axis. Set a value to AST__BAD to indicate that the axis has no lower limit.
ubnd - An array of double, with one element for each Frame axis (Naxes attribute) containing the upper limits on each axis. Set a value to AST__BAD to indicate that the axis has no upper limit.
unc - An optional pointer to an existing Region which specifies the uncertainties associated with the boundary of the Box being created. The uncertainty in any point on the boundary of the Box is found by shifting the supplied "uncertainty" Region so that it is centred at the boundary point being considered. The area covered by the shifted uncertainty Region then represents the uncertainty in the boundary position. The uncertainty is assumed to be the same for all points.

If supplied, the uncertainty Region must be of a class for which all instances are centro-symetric (e.g. Box, Circle, Ellipse, etc.) or be a Prism containing centro-symetric component Regions. A deep copy of the supplied Region will be taken, so subsequent changes to the uncertainty Region using the supplied pointer will have no effect on the created Box. Alternatively, a NULL Object pointer may be supplied, in which case a default uncertainty is used equivalent to a box 1.0E-6 of the size of the Box being created.

The uncertainty Region has two uses: 1) when the astOverlap function compares two Regions for equality the uncertainty Region is used to determine the tolerance on the comparison, and 2) when a Region is mapped into a different coordinate system and subsequently simplified (using astSimplify), the uncertainties are used to determine if the transformed boundary can be accurately represented by a specific shape of Region.

Throws:
AstException - if an error occurred in the AST library


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