MITgcm_contrib/gmaze_pv/subfct_getsurf.m

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Master function:

function varargout = subfct_getsurf(CHP,Y,X,LIMITS)

% Limits:
%disp(strcat('Limits: ',num2str(LIMITS)));
O  = LIMITS(1);
MY = sort( LIMITS(2:3) );
MX = sort( LIMITS(4:5) );

% Compute the surface:
[S Smat dS] = getsurf(Y,X,O,MY,MX,CHP);

% Outputs:
switch nargout
 case 1
  varargout(1) = {S};
 case 2
  varargout(1) = {S};
  varargout(2) = {Smat};
 case 3
  varargout(1) = {S};
  varargout(2) = {Smat};
  varargout(3) = {dS};
end %switch nargout


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This function computes the surface limited southward by
% MY(1), northward by iso-O (or MY(2) if iso-O reaches it),
% eastward by MX(1), westward by MX(2) 
function varargout = getsurf(Y,X,O,MY,MX,CHP)

%% Dim:
ny = length(Y);
nx = length(X);
%disp(num2str([ny nx]));
%% Indices:
iymin = min( find( Y>=MY(1) ) );
iymax = min( find( Y>=MY(2) ) );
ixmin = min( find( X>=MX(1) ) );
ixmax = min( find( X>=MX(2) ) );
%disp(num2str([iymin iymax ixmin ixmax]));

%% 1- determine the 2D matrix of surface elements defined by
% the grid:
dS = getdS(Y,X);

%% 2- compute the 2D surface matrix where 1 means dS must be 
% counted and 0 must not:

S = ones(ny,nx); % initialy keep all points

% Exclude northward iso-O limits:
% NB: here the test depends on the meridional gradient of CHP
%     if CHP increase (resp. decreases) with LAT then we must
%     keep lower (resp. higher) values than iso-O limit
% a: determine test type:
N = iymax - iymin + 1; % Number of Y points in the domain
CHPsouth = nanmean(nanmean(squeeze(CHP(iymin:iymin+fix(N/2),ixmin:ixmax))));
CHPnorth = nanmean(nanmean(squeeze(CHP(iymin+fix(N/2):iymax,ixmin:ixmax))));
SNgrad = (CHPnorth - CHPsouth)./abs(CHPnorth - CHPsouth);
%disp(strcat('Northward gradient sign is:',num2str(SNgrad)));
switch SNgrad
 case  1, testype = 'le'; % Less than  or equal 
 case -1, testype = 'ge'; % Greater than or equal
end %switch
% b: exclude points
S = double(feval(testype,CHP,O));

% Exclude southward limit:
S(1:iymin,:) = zeros(iymin,nx);

% Exclude northward limit:
S(iymax:ny,:) = zeros((ny-iymax)+1,nx);

% Exclude westward limit:
S(:,1:ixmin) = zeros(ny,ixmin);

% Exclude eastward limit:
S(:,ixmax:nx) = zeros(ny,(nx-ixmax)+1);


%% 3- Then compute the surface by summing dS elements 
%     for non nul S points
Skeep = S.*dS;
Skeep = sum(sum(sum(Skeep)));

%% 4- Outputs:
switch nargout
 case 1
  varargout(1) = {Skeep}; % Surface single value
 case 2
  varargout(1) = {Skeep};
  varargout(2) = {S};     % Logical S matrix with included/excluded points
 case 3
  varargout(1) = {Skeep};
  varargout(2) = {S};
  varargout(3) = {dS};    % Surface elements matrix
end %switch nargout


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This function computes the 2D dS surface elements.
function ds = getdS(Y,X);

ny = length(Y);
nx = length(X);

%%% Compute the DY:
% Assuming Y is independant of ix:
d  = m_lldist([1 1]*X(1),Y);
dy = [d(1)/2  (d(2:length(d))+d(1:length(d)-1))/2 d(length(d))/2];
dy = meshgrid(dy,X)';

%%% Compute the DX:
clear d
for iy = 1 : ny
   d(:,iy) = m_lldist(X,Y([iy iy]));
end
dx = [d(1,:)/2 ;  ( d(2:size(d,1),:) + d(1:size(d,1)-1,:) )./2 ; d(size(d,1),:)/2];
dx = dx';

%% Compute the horizontal DS surface element:
ds = dx.*dy;

1	gmaze	1.1	%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2			% Master function:
3
4			function varargout = subfct_getsurf(CHP,Y,X,LIMITS)
5
6			% Limits:
7			%disp(strcat('Limits: ',num2str(LIMITS)));
8			O = LIMITS(1);
9			MY = sort( LIMITS(2:3) );
10			MX = sort( LIMITS(4:5) );
11
12			% Compute the surface:
13			[S Smat dS] = getsurf(Y,X,O,MY,MX,CHP);
14
15			% Outputs:
16			switch nargout
17			case 1
18			varargout(1) = {S};
19			case 2
20			varargout(1) = {S};
21			varargout(2) = {Smat};
22			case 3
23			varargout(1) = {S};
24			varargout(2) = {Smat};
25			varargout(3) = {dS};
26			end %switch nargout
27
28
29			%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
30			% This function computes the surface limited southward by
31			% MY(1), northward by iso-O (or MY(2) if iso-O reaches it),
32			% eastward by MX(1), westward by MX(2)
33			function varargout = getsurf(Y,X,O,MY,MX,CHP)
34
35			%% Dim:
36			ny = length(Y);
37			nx = length(X);
38			%disp(num2str([ny nx]));
39			%% Indices:
40			iymin = min( find( Y>=MY(1) ) );
41			iymax = min( find( Y>=MY(2) ) );
42			ixmin = min( find( X>=MX(1) ) );
43			ixmax = min( find( X>=MX(2) ) );
44			%disp(num2str([iymin iymax ixmin ixmax]));
45
46			%% 1- determine the 2D matrix of surface elements defined by
47			% the grid:
48			dS = getdS(Y,X);
49
50			%% 2- compute the 2D surface matrix where 1 means dS must be
51			% counted and 0 must not:
52
53			S = ones(ny,nx); % initialy keep all points
54
55			% Exclude northward iso-O limits:
56			% NB: here the test depends on the meridional gradient of CHP
57			% if CHP increase (resp. decreases) with LAT then we must
58			% keep lower (resp. higher) values than iso-O limit
59			% a: determine test type:
60			N = iymax - iymin + 1; % Number of Y points in the domain
61			CHPsouth = nanmean(nanmean(squeeze(CHP(iymin:iymin+fix(N/2),ixmin:ixmax))));
62			CHPnorth = nanmean(nanmean(squeeze(CHP(iymin+fix(N/2):iymax,ixmin:ixmax))));
63			SNgrad = (CHPnorth - CHPsouth)./abs(CHPnorth - CHPsouth);
64			%disp(strcat('Northward gradient sign is:',num2str(SNgrad)));
65			switch SNgrad
66			case 1, testype = 'le'; % Less than or equal
67			case -1, testype = 'ge'; % Greater than or equal
68			end %switch
69			% b: exclude points
70			S = double(feval(testype,CHP,O));
71
72			% Exclude southward limit:
73			S(1:iymin,:) = zeros(iymin,nx);
74
75			% Exclude northward limit:
76			S(iymax:ny,:) = zeros((ny-iymax)+1,nx);
77
78			% Exclude westward limit:
79			S(:,1:ixmin) = zeros(ny,ixmin);
80
81			% Exclude eastward limit:
82			S(:,ixmax:nx) = zeros(ny,(nx-ixmax)+1);
83
84
85			%% 3- Then compute the surface by summing dS elements
86			% for non nul S points
87			Skeep = S.*dS;
88			Skeep = sum(sum(sum(Skeep)));
89
90			%% 4- Outputs:
91			switch nargout
92			case 1
93			varargout(1) = {Skeep}; % Surface single value
94			case 2
95			varargout(1) = {Skeep};
96			varargout(2) = {S}; % Logical S matrix with included/excluded points
97			case 3
98			varargout(1) = {Skeep};
99			varargout(2) = {S};
100			varargout(3) = {dS}; % Surface elements matrix
101			end %switch nargout
102
103
104
105			%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
106			% This function computes the 2D dS surface elements.
107			function ds = getdS(Y,X);
108
109			ny = length(Y);
110			nx = length(X);
111
112			%%% Compute the DY:
113			% Assuming Y is independant of ix:
114			d = m_lldist([1 1]*X(1),Y);
115			dy = [d(1)/2 (d(2:length(d))+d(1:length(d)-1))/2 d(length(d))/2];
116			dy = meshgrid(dy,X)';
117
118			%%% Compute the DX:
119			clear d
120			for iy = 1 : ny
121			d(:,iy) = m_lldist(X,Y([iy iy]));
122			end
123			dx = [d(1,:)/2 ; ( d(2:size(d,1),:) + d(1:size(d,1)-1,:) )./2 ; d(size(d,1),:)/2];
124			dx = dx';
125
126			%% Compute the horizontal DS surface element:
127			ds = dx.*dy;
128