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Re: How to make IDL faster [message #36868 is a reply to message #36775]

Wed, 29 October 2003 11:18

MKatz843
Messages: 98
Registered: March 2002

Member

> for i=0,207 do begin
> for j=1200,1700 do begin
> for k=0,di(0)-1 do begin
>
> if geo(0,i,j) gt lat(k)-0.04 and geo(0,i,j) lt lat(k)+0.04 and $
> geo(1,i,j) gt lon(k)-0.04 and geo(1,i,j) lt lon(k)+0.04 then begin
> printf,lun3,loc(k),lon(k),lat(k),rain1(k),rain(k),highf(0,i, j)
> endif
>
> endfor
> endfor
> endfor
>
> How can I change this program?
> Help me.

This is minor, but you can get a small speed advantage by taking out
the begin...end where possible. For example your code could be

for i=0,207 do $
for j=1200,1700 do $
for k=0,di(0)-1 do $
if geo(0,i,j) gt lat(k)-0.04 and geo(0,i,j) lt lat(k)+0.04 and $
geo(1,i,j) gt lon(k)-0.04 and geo(1,i,j) lt lon(k)+0.04 $
then printf,lun3,loc(k),lon(k),lat(k),rain1(k),rain(k),highf(0,i, j)

It makes a small difference but it can help. You have to use
begin...end only when there is more than one line of code to execute.
Here, you can string them together.

You could change

if geo(0,i,j) gt lat(k)-0.04 and geo(0,i,j) lt lat(k)+0.04 and $
geo(1,i,j) gt lon(k)-0.04 and geo(1,i,j) lt lon(k)+0.04

to this

if (abs(geo(0,i,j) - lat(k)) LT 0.04) and $
(abs(geo(1,i,j) - lon(k)) LT 0.04) then . . .

Here I am thinking that you minimize the number of times you have to
go to the geo() array and get the (0,i,j) element.

M. Katz

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[Message index]

		How to make IDL faster By: parkkw on Tue, 28 October 2003 21:35
		Re: How to make IDL faster By: Robert Moss on Sun, 02 November 2003 09:17
		Re: How to make IDL faster By: the_cacc on Mon, 03 November 2003 10:37
		Re: How to make IDL faster By: the_cacc on Fri, 31 October 2003 18:49
		Re: How to make IDL faster By: parkkw on Wed, 29 October 2003 16:35
		Re: How to make IDL faster By: Ken Knapp on Wed, 29 October 2003 13:28
		Re: How to make IDL faster By: mchinand on Wed, 29 October 2003 11:42
		Re: How to make IDL faster By: MKatz843 on Wed, 29 October 2003 11:18

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