;+ ; NAME: ; sinterp4 ; PURPOSE: (one line) ; Four-fold sinc interpolation of a vector of data. ; DESCRIPTION: ; This function will do a 4-fold sinc interpolation of the data ; array that is passed. ; CATEGORY: ; Numerical ; CALLING SEQUENCE: ; result = sinterp4( x ) ; INPUTS: ; x : Input data array. ; OPTIONAL INPUT PARAMETERS: ; ; KEYWORD PARAMETERS: ; ; OUTPUTS: ; The interpolated array is returned as the function value. ; COMMON BLOCKS: ; ; SIDE EFFECTS: ; ; RESTRICTIONS: ; ; PROCEDURE: ; ; MODIFICATION HISTORY: ; Original C-Language version written by: Marc W. Buie, Institute for ; Astronomy, University of Hawaii. Date: 9 December 1987. ; Adapted for IDL by Doug Loucks, Lowell Observatory, September 2, 1993. ;- FUNCTION sinterp4, x n = N_ELEMENTS( x ) r = FLTARR( 4, n ) r[ 0, * ] = x r[ 1, * ] = sshift( x, -0.25 ) r[ 2, * ] = sshift( x, -0.50 ) r[ 3, * ] = sshift( x, -0.75 ) RETURN, r[ INDGEN( 4 * n - 3 ) ] END