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Re: realizing the formula in idl [message #45405 is a reply to message #45403]

Fri, 09 September 2005 01:40

Timm Weitkamp
Messages: 66
Registered: August 2002

Member

pravesh.subramanian@gmail.com wrote:

> How do I realize this formula in IDL?
>
> matrix(x, y) = 1/(s^2 * 2 * pi) * Exp (-(x^2 + y^2)/2 * s^2)
>
> let's say x = y = 300

I assume that by "x = y = 300" you actually mean that x and y are 1D
arrays with approximately 300 elements each, right? The formula then
describes a 2D Gaussian with width "s". Here is a way of doing it:

s = 100.0 ; or whatever other value you want for the width
nx = 300 ; number of elements of x
ny = 300 ; number of elements of y
x = FINDGEN(nx) ; your x values
y = FINDGEN(ny) ; your y values

; Blow x and y up to two dimensions

xx = x # (1.0 + FLTARR(ny))
yy = y ## (1.0 + FLTARR(nx))

; ... and then the calculation of the Gaussian is as easy as this:

matrix = 1.0 / (s^2 * 2 * !PI) * EXP(-(xx^2 + yy^2) / (2.0 * s^2))

Hope this helps,
Timm

Timm Weitkamp
ESRF, Grenoble, France

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[Message index]

		Re: realizing the formula in idl By: pravesh.subramanian on Fri, 09 September 2005 07:44
		Re: realizing the formula in idl By: James Kuyper on Fri, 09 September 2005 07:14
		Re: realizing the formula in idl By: Craig Markwardt on Fri, 09 September 2005 00:57
		Re: realizing the formula in idl By: Timm Weitkamp on Fri, 09 September 2005 01:40

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