From 855e0053c56bbe2555e87b180f3bf3f3ecccf121 Mon Sep 17 00:00:00 2001
From: Eugeniy Mikhailov <evgmik@gmail.com>
Date: Wed, 13 Apr 2011 11:06:02 -0400
Subject: extra comments

Ignore-this: 24148ddf66f49e2b8c4f02186a8dbc3b

darcs-hash:20110413150602-067c0-b7e0f6ccfca349018b313e5ac53859557e189582
---
 abcd.m | 41 ++++++++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 19 deletions(-)

(limited to 'abcd.m')

diff --git a/abcd.m b/abcd.m
index 7e02200..ac9b1db 100644
--- a/abcd.m
+++ b/abcd.m
@@ -10,12 +10,32 @@ function qnew=q_afteer_element(q_old,abcd)
 	qnew=(q_old*abcd(1,1)+abcd(1,2))/(q_old*abcd(2,1)+abcd(2,2));
 endfunction
 
+
+function optics = arrange_optics_along_x(optics_unsorted)
+% arrange optics in proper order so it x position increases with number
+	N=length(optics_unsorted);
+
+	% assign x positions
+	x=zeros(1,N);
+	for i=1:N
+		x(i)=optics_unsorted{i}.x;
+	end
+
+	[xs,indx]=sort(x);
+	cntr=1;
+	for i=indx
+		optics{cntr}=optics_unsorted{i};
+		cntr=cntr+1;
+	end
+end
+
 function q = prop_forward(x_pos, q_in, x_in,  optics_elements)
 % calculate the 'q' parameter of the Gaussian beam propagating through optical
-% 'optics_elements' array along 'x' axis at points 'x_pos'
+% 'optics_elements' only in the positive direction  along 'x' axis at points 'x_pos'
 %  takes the gaussian beam with initial q_in parameter at x_in
 %
 % all x_pos must be to the right of x_in
+% x_pos must be monotonic!
 	if (any(x_pos < x_in))
 		error('all beam positions must be to the right of the x_in');
 	end
@@ -50,28 +70,11 @@ function q = prop_forward(x_pos, q_in, x_in,  optics_elements)
 	endfor
 end
 
-function optics = arrange_optics_along_x(optics_unsorted)
-% arrange optics in proper order so it x position increases with number
-	N=length(optics_unsorted);
-
-	% assign x positions
-	x=zeros(1,N);
-	for i=1:N
-		x(i)=optics_unsorted{i}.x;
-	end
-
-	[xs,indx]=sort(x);
-	cntr=1;
-	for i=indx
-		optics{cntr}=optics_unsorted{i};
-		cntr=cntr+1;
-	end
-end
-
 function q = prop(x_pos, q_in, x_in,  optics_elements)
 % calculate the 'q' parameter of the Gaussian beam propagating through optical
 % 'optics_elements' array along 'x' axis at points 'x_pos'
 %  takes the gaussian beam with initial q_in parameter at x_in
+% x_pos must be monotonic!
 
 	q=0*x_pos; % q vector initialization
 
-- 
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