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Perform a linear transform between input and output vectors. More...
#include <LinearXform.h>
Public Member Functions | |
LinearXform (uInt naxis=1) | |
Construct with specified number of axes. | |
LinearXform (const Vector< Double > &crpix, const Vector< Double > &cdelt) | |
Construct the linear transformation from the supplied reference pixel and increment. | |
LinearXform (const Vector< Double > &crpix, const Vector< Double > &cdelt, const Matrix< Double > &pc) | |
Construct a linear transformation, supplying all of the reference pixel, increment and PC matrix. | |
LinearXform (const LinearXform &other) | |
Copy constructor (copy sematics). | |
LinearXform & | operator= (const LinearXform &other) |
Assignment (copy sematics). | |
~LinearXform () | |
Destructor. | |
uInt | nWorldAxes () const |
Returns the number of world axes, which for this class is also the number of pixel axes. | |
Bool | forward (Vector< Double > &pixel, const Vector< Double > &world, String &errorMsg) const |
Convert world coordinates to pixel coordinates (forward), or pixel coordinates to world (reverse). | |
Bool | reverse (Vector< Double > &world, const Vector< Double > &pixel, String &errorMsg) const |
Vector< Double > | crpix () const |
Retrieve the value of crpix, cdelt, and pc. | |
Vector< Double > | cdelt () const |
Matrix< Double > | pc () const |
void | crpix (const Vector< Double > &newvals) |
Set the value of crpix, cdelt, and pc. | |
void | cdelt (const Vector< Double > &newvals) |
void | pc (const Matrix< Double > &newvals) |
LinearXform * | fourierInvert (String &errMsg, const Vector< Bool > &axes, const Vector< Double > &crpix, const Vector< Double > &scale) const |
Invert the LinearXform ready for use in a Fourier Transformed Coordinate. | |
Bool | near (const LinearXform &other, Double tol=1e-6) const |
Comparison function. | |
Bool | near (const LinearXform &other, const Vector< Int > &excludeAxes, Double tol=1e-6) const |
Private Member Functions | |
void | set_linprm () |
Private Attributes | |
linprm | linprm_p |
A WCSLIB C-structure. | |
Bool | isPCDiagonal_p |
Perform a linear transform between input and output vectors.
Internal
This class represents the common linear part of a FITS coordinate transformation. In particular it does the following:
world = cdelt * PC * (pixel - crpix)
Where PC is an NxN matrix; pixel, crpix (reference pixel) and world are length N vectors; and cdelt (increment) is an NxN diagonal matrix, represented as a length N vector.
Normally this class isn't used directly, rather it is used indirectly through a class like LinearCoordinate .
The actual computations are performed by WCSLIB, written by Mark Calabretta of the ATNF.
Let's make a LinearXform housing two axes with a unit diagonal PC matrix and convert from pixel to world
Vector<Double> crpix(2), cdelt(2); crpix(0) = 10.0; crpix(1) = 20.0; cdelt(0) = 1.0; cdelt(1) = -1.0; LinearXform lxf(crpix, cdelt); String errMsg; Vector<Double> world, pixel(2); pixel = 10.0; Bool ok = lxf.reverse(world, pixel, errMsg); if (ok) { cerr << "pixel, world = " << pixel << world << endl; } else { cerr << "Error : " << errMsg << endl; }
The answer should be a world vector with values 0 and -10.
Factor out the common linear part of coordinate transformations.
Definition at line 109 of file LinearXform.h.
casa::LinearXform::LinearXform | ( | uInt | naxis = 1 |
) |
Construct with specified number of axes.
The reference pixel is assumed to be 0, and the increment is assumed to be unity, and the PC matrix is assumed to be diagonal.
Construct the linear transformation from the supplied reference pixel and increment.
The PC matrix is the unit matrix. crpix
and cdelt
must have the same number of elements.
casa::LinearXform::LinearXform | ( | const Vector< Double > & | crpix, | |
const Vector< Double > & | cdelt, | |||
const Matrix< Double > & | pc | |||
) |
Construct a linear transformation, supplying all of the reference pixel, increment and PC matrix.
The vectors must be of the same length ("n") and the number of rows and columns in the matrix must also be n.
casa::LinearXform::LinearXform | ( | const LinearXform & | other | ) |
Copy constructor (copy sematics).
casa::LinearXform::~LinearXform | ( | ) |
Destructor.
Set the value of crpix, cdelt, and pc.
Note that since you can only set one of them, you cannot change the dimensionality of the transform using these functions. Instead use assignment on a temporary, i.e.: linxform = LinearXform (crpix,crval,pc);
Bool casa::LinearXform::forward | ( | Vector< Double > & | pixel, | |
const Vector< Double > & | world, | |||
String & | errorMsg | |||
) | const |
Convert world coordinates to pixel coordinates (forward), or pixel coordinates to world (reverse).
If the conversion works True is returned, otherwise False is returned and errorMsg is set. The output vectors are resized appropriately.
LinearXform* casa::LinearXform::fourierInvert | ( | String & | errMsg, | |
const Vector< Bool > & | axes, | |||
const Vector< Double > & | crpix, | |||
const Vector< Double > & | scale | |||
) | const |
Invert the LinearXform ready for use in a Fourier Transformed Coordinate.
It is the callers responsibility to delete the pointer. If it fails the pointer is 0 and an error message is provided
Bool casa::LinearXform::near | ( | const LinearXform & | other, | |
const Vector< Int > & | excludeAxes, | |||
Double | tol = 1e-6 | |||
) | const |
Bool casa::LinearXform::near | ( | const LinearXform & | other, | |
Double | tol = 1e-6 | |||
) | const |
Comparison function.
Any private Double data members are compared with the specified fractional tolerance. You can specify axes to exclude from the comparison if you wish.
uInt casa::LinearXform::nWorldAxes | ( | ) | const |
Returns the number of world axes, which for this class is also the number of pixel axes.
LinearXform& casa::LinearXform::operator= | ( | const LinearXform & | other | ) |
Assignment (copy sematics).
Bool casa::LinearXform::reverse | ( | Vector< Double > & | world, | |
const Vector< Double > & | pixel, | |||
String & | errorMsg | |||
) | const |
void casa::LinearXform::set_linprm | ( | ) | [private] |
Bool casa::LinearXform::isPCDiagonal_p [private] |
Definition at line 193 of file LinearXform.h.
linprm casa::LinearXform::linprm_p [mutable, private] |
A WCSLIB C-structure.
Definition at line 191 of file LinearXform.h.