Local_Trig_Interval Struct Reference

Information to do a local trigonometric transform on an interval. More...

#include <libftsh.h>

Data Fields
int	numpts
int	left_extra
int	right_extra
int	fcn_offset
int	coef_offset
REAL *	bell
REAL *	dualbell
int	which_transform
Ftrigtw_Plan	transform_plan

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Detailed Description

Information to do a local trigonometric transform on an interval.

NOTES:

• It assumes the function values and coeffiecients are each stored in a contiguous array, and so is not compatible with multidimensional blocking.
• Eventually allow
  • which_transform==2 --> Discrete Sine Transform and
  • which_transform==3 --> Local Sine Transform

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Field Documentation

REAL* bell

A pointer to the precomputed bell values for the expansion transform. When in use, points to left_extra+numpts+right_extra REALs

int coef_offset

An offset telling where our subinterval starts within the full array of coefficient values. Generally this does NOT represent a physical location, because we leave room for various other redundant representations of the same physical location.

REAL* dualbell

A pointer to the precomputed bell values for the evaluation transform. When in use, points to left_extra+numpts+right_extra REALs. If the bell used was orthogonal then the bell and dualbell values are the same.

int fcn_offset

An offset telling where our subinterval starts within the full array of function values. Generally this represents a physical location.

int left_extra

The amount the bell spills to the left of the main interval.

int numpts

The number of points in the selected interval. Also is the number of coefficients produced.

int right_extra

The amount the bell spills to the right of the main interval.

Ftrigtw_Plan transform_plan

A structure that holds precomputed things used by the trig transform itself.

int which_transform

A flag telling us which local trigonometric transform to use. This also tells us the parity of the folds at the two edges. Current legal values are:

• 0 -- Local Cosine Transform (dct4). Even fold at the left and odd fold at the right
• 1 -- Discrete Cosine Transform. Even folds at both edges
• 9 -- no transform, no bell; simple copy

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

• libftsh.h