;+
; NAME:
;  arrgen
; PURPOSE: (one line)
;  generate an array of evenly spaced numbers
; DESCRIPTION:
;  
; CATEGORY:
;  Util
; CALLING SEQUENCE:
;  arrgen, x0, x1, dx
; INPUTS:
;  x0 = initial value
;  x1 = final value
;  dx = approximate difference between successive values
; OPTIONAL INPUT PARAMETERS:
;  int = 1 if integer
;  long = 1 if long
;  float = 1 if float
;  double = 1 if double
;  
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
; COMMON BLOCKS:
;  None
; SIDE EFFECTS:
; RESTRICTIONS:
;  None
; PROCEDURE:
; MODIFICATION HISTORY:
;  2005 Mar 16 Leslie Young SwRI Moved to layoung/util
;  2009 Oct 15 LAY adjust spacing to hit x1 exacctly
;-



function arrgen, x0, x1, dx, int=int, long=long, float=float, double=double

    if n_params() lt 3 then dx = 1

    if keyword_set(double) then begin
        nx = ceil((x1-x0)/dx) + 1
;        x = x0 + dindgen(nx)*dx
        x = x0 + dindgen(nx)*(x1-x0)/(nx-1.)
        return, x
    end

    if keyword_set(float) then begin
        nx = ceil((x1-x0)/dx) + 1
;        x = x0 + findgen(nx)*dx
        x = x0 + findgen(nx)*(x1-x0)/(nx-1.)
        return, x
    end

    if keyword_set(long) then begin
        i0 = floor(x0)
        i1 = ceil(x1)
        nx = ceil((i1-i0)/dx) + 1
        x = i0 + lindgen(nx)*dx
        return, x
    end

    if keyword_set(int) then begin
        i0 = floor(x0)
        i1 = ceil(x1)
        nx = ceil((i1-i0)/dx) + 1
        x = i0 + indgen(nx)*dx
        return, x
    end

    nx = ceil((x1-x0)/dx) + 1
;    x = x0 + findgen(nx)*dx
    x = x0 + findgen(nx)*(x1-x0)/(nx-1.)
    return, x
    
end