IrregularTransformation class resource descriptions

trXAxisType
This resource of type NhlTAxisType sets the type of transformation used for the X Axis. It has three possible settings:
IrregularAxis
Based on the values of the trXCoordPoints resource (and possibly the trXInterPoints resource), an irregular coordinate system is defined along the X Axis. If trXCoordPoints is unset or found to be invalid, a warning will be issued and trXAxisType will be reset to its default value: LinearAxis.
LogAxis
A logarithmic coordinate system is established for the X Axis with boundaries defined by the values of trXMinF and trXMaxF. If trXMinF is less than or equal to 0.0, a warning will be issued and trXAxisType will be reset to its default value: LinearAxis.
LinearAxis
A linear coordinate system is established for the X Axis with boundaries defined by the values of trXMinF and trXMaxF.

This resource may be intercepted or disabled by:

Default: LinearAxis

trXCoordPoints
If trXInterPoints is not set, this array resource represents uniformly spaced samples of a bounded irregularly spaced data coordinate system along the X Axis. The elements of the array must be arranged in a monotonically increasing or decreasing order. The coordinate system bounds are defined as the values of the minimum and maximum elements of the array: in other words, its first and last elements. If you superimpose on this coordinate system a regular coordinate system such that the left end is 0 and the right end is the number of elements in the array minus 1, then each succeeding array element value represents the coordinate value of the irregular coordinate system at successive integral coordinate points (0, 1, 2, ...) of the overlaid regular coordinate system. Note that these integral coordinates correspond directly to the array element index (with an offset of 1 when using a Fortran interface). Based on this mapping, the IrregularTransformation sets up both a forward and a reverse transformation.

trXCoordPoints is ignored unless trXAxisType is set to IrregularAxis. If the array contains less than two points or is non-monotonic, a warning will be issued and trXAxisType will be reset to its default value: LinearAxis.

V4.1 Status Note 2

This resource may be intercepted or disabled by:

Default: NULL

trXInterPoints
This array resource, which, if set, must contain the same number of points as trXCoordPoints, adds another step to the mapping from regular to irregular coordinates. As in the case when trXInterPoints is not set, you superimpose a bounded regular coordinate system on the irregular coordinate system. Successive elements of trXInterPoints, like those of trXCoordPoints, must increase or decrease monotonically. However, the element values have a range defined by the bounds of the superimposed regular coordinate system (0 through array size - 1). Now the location of the data coordinate point specified by each successive element of the trXCoordPoints is determined, not by direct correlation with its array index, but by the value of the corresponding element of the trXInterPoints array.

trXInterPoints is ignored unless trXAxisType is set to IrregularAxis. If trXInterPoints is found to be invalid, IrregularTransformation issues a warning message and computes the coordinate transformation as if it had not been set.

This resource may be intercepted or disabled by:

Default: NULL

trXTensionF
Specifies the value of the tension parameter applied to the spline approximation used to set up the irregular transformation for the X Axis coordinate system. Small values (less than ~1.0) imply a relaxed approximation; large values (greater than ~5.0) imply a tight approximation. Note that large values of this parameter (>~10.0) may cause the transformation to become unstable or even fail.

Default: 2.0

trXSamples
Specifies the number of sample points over the X-Axis coordinate system that IrregularTransformation is to use in order to determine the reverse transformation. More sample points (usually) increase the accuracy of the reverse transformation, but at the cost of greater processing time for every transformation calculated.

This resource may be intercepted or disabled by:

Default: 9

trYAxisType
This resource of type NhlTAxisType sets the type of transformation used for the Y Axis. It has three possible settings:
IrregularAxis
Based on the values of the trYCoordPoints resource (and possibly the trYInterPoints resource), an irregular coordinate system is defined along the Y Axis. If trYCoordPoints is unset or found to be invalid, a warning will be issued and trYAxisType will be reset to its default value: LinearAxis.
LogAxis
A logarithmic coordinate system is established for the Y Axis with boundaries defined by the values of trYMinF and trYMaxF. If trYMinF is less than or equal to 0.0, a warning will be issued and trYAxisType will be reset to its default value: LinearAxis.
LinearAxis
A linear coordinate system is established for the Y Axis with boundaries defined by the values of trYMinF and trYMaxF.

This resource may be intercepted or disabled by:

Default: LinearAxis

trYCoordPoints
If trYInterPoints is not set, this array resource represents uniformly spaced samples of a bounded, irregularly spaced data coordinate system along the Y Axis. The elements of the array must be arranged in a monotonically increasing or decreasing order. The coordinate system bounds are defined as the values of the minimum and maximum elements of the array: in other words, its first and last elements. If you superimpose on this coordinate system a regular coordinate system such that the bottom end is 0 and the top end is the number of elements in the array minus 1, then each succeeding array element value represents the coordinate value of the irregular coordinate system at successive integral coordinate points (0, 1, 2, ...) of the overlaid regular coordinate system. Note that these integral coordinates correspond directly to the array element index (with an offset of 1 when using a Fortran interface). Based on this mapping, the IrregularTransformation sets up both a forward and a reverse transformation.

trYCoordPoints is ignored unless trYAxisType is set to IrregularAxis. If the array contains less than two points or is non-monotonic, a warning will be issued and trYAxisType will be reset to its default value: LinearAxis.

This resource may be intercepted or disabled by:

V4.1 Status Note 2

Default: NULL

trYInterPoints
This array resource, which, if set, must contain the same number of points as trYCoordPoints, adds another step to the mapping from regular to irregular coordinates. As in the case when trYInterPoints is not set, you superimpose a bounded regular coordinate system on the irregular coordinate system. Successive elements of trYInterPoints, like those of trYCoordPoints, must increase or decrease monotonically. However, the element values have a range defined by the bounds of the superimposed regular coordinate system (0 through array size -1). Now the location of the data coordinate point specified by each successive element of the trYCoordPoints is determined, not by direct correlation with its array index, but by the value of the corresponding element of the trYInterPoints array.

trYInterPoints is ignored unless trYAxisType is set to IrregularAxis. If trYInterPoints is found to be invalid, IrregularTransformation issues a warning message and computes the coordinate transformation as if it had not been set.

This resource may be intercepted or disabled by:

Default: NULL

trYTensionF
Specifies the value of the tension parameter applied to the spline approximation used to set up the irregular transformation for the Y Axis coordinate system. Small values (less than ~1.0) imply a relaxed approximation; large values (greater than ~5.0) imply a tight approximation. Note that large values of this parameter (>~10.0) may cause the transformation to become unstable or even fail.

Default: 2.0

trYSamples
Specifies the number of sample points over the Y-Axis coordinate system that IrregularTransformation is to use in order to determine the reverse transformation. More sample points (usually) increase the accuracy of the reverse transformation, but at the cost of greater processing time for every transformation calculated.

This resource may be intercepted or disabled by:

Default: 9


Reference Manual Control Panel

NG4.1 Home, Index, Examples, Glossary, Feedback, Ref Contents, Ref WhereAmI?


$Revision: 1.3 $ $Date: 1998/08/17 21:08:55 $