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How to arrange coordinates into 3 columns?

Asked by Oscar Espinosa on 15 Aug 2019
Latest activity Commented on by Rik
on 15 Aug 2019
I'm creating the mesh of a wing, so, in order to export the coordinates of each node I need to arrange all the coordinates (x,y,z) into three columns.
By the moment I have agrouped the coordinates into three section, each one correspont to each coordinate. But I would like to organize them in such a way that each column continues to be a single column until the last one corresponding to that coordinate (x or y or z). I hope I have explained myself, I also attached an image and the code.Thanks in advance
150519 Orden de columnas.png
function WINGEODISC
%% Read airfoil
FILEID = fopen('A_prof.txt','r');
FORMATSPEC = '%f %f'; % %d times should correspont to m
SIZEXZ = [3 Inf]; % [m,n] n can be Inf, but m cannot.
XZ = fscanf(FILEID,FORMATSPEC,SIZEXZ);
fclose(FILEID);
XZ = XZ';
XP_AIRFOIL = XZ(:,1);
ZP_AIRFOIL = XZ(:,2);
%% Wing definitions
MAIN_NODES_X = ones(4,4);
%SPAN = 10;
AREA = 7.5;
AR = 13.3333;
LE_SWEPT = 30; % Swept wing - Стреловидность - Flechamiento [deg]
%TE_SWEPT = 0; % Trailing edge
TAPER = 2;
SEMISPAN = sqrt(AR*AREA)/2;
CHORD_ROOT = 2*AREA*TAPER/(TAPER+1)/SEMISPAN
CHORD_TIP = CHORD_ROOT/TAPER;
MAIN_NODES_X = [0 CHORD_ROOT; tan(degtorad(LE_SWEPT)) CHORD_TIP+tan(degtorad(LE_SWEPT))]
MAIN_NODES_Y = [0 0; SEMISPAN SEMISPAN]
%% Wing discretization
%
NX = 13;
NY = 3;
XP_NODES = ones(NY,NX);
YP_NODES = ones(NY,NX);
ZP_NODES = ones(NY,NX);
DELTA_LX = CHORD_ROOT/NX;
DELTA_LY = SEMISPAN/NY;
XP_NODES(1,:) = linspace(0,CHORD_ROOT,NX).*XP_AIRFOIL';
ZP_NODES(1,:) = CHORD_ROOT*XZ(:,2)';
%ZP_NODES(1,:) = linspace(0,CHORD_ROOT,NX).*ZP_AIRFOIL';
%XP_NODES(1,:) = XP_NODES(1,:).*XP_AIRFOIL'
XP_NODES(end,:) = linspace(0,CHORD_TIP,NX)+tan(degtorad(LE_SWEPT)).*XP_AIRFOIL';
%XP_NODES = linspace(0,CHORD_TIP)
ZP_NODES(end,:) = CHORD_TIP.*XZ(:,2)';
MESH = [XP_NODES' YP_NODES' ZP_NODES']
%%
%}
end

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1 Answer

Answer by Rik
on 15 Aug 2019
 Accepted Answer

If you want to linearize an array, you can use (:):
[XP_NODES,YP_NODES,ZP_NODES]=deal(XP_NODES',YP_NODES',ZP_NODES');
MESH = [XP_NODES(:) YP_NODES(:) ZP_NODES(:)];

  2 Comments

Thank you Rik, now I'm trying to save that data to a file using the next code:
MESH = [XP_NODES(:) YP_NODES(:) ZP_NODES(:)];
fileID = fopen('mesh.txt','w');
fprintf(fileID,' %12.10f %12.10f %12.10f \r\n',MESH);
fclose(fileID);
but what I'm getting its the next .txt file:
0.0000000000 1.0000000000 0.0000000000
0.0041666719 1.0000000000 0.0977671942
0.0166666875 1.0000000000 0.1955343885
0.0500000625 1.0000000000 0.3077353394
0.1333335000 1.0000000000 0.4488038038
0.2500003125 1.0000000000 0.5898722683
0.4000005000 1.0000000000 0.7309407327
0.5833340625 1.0000000000 0.8720091971
0.8000010000 1.0000000000 1.0130776615
1.0500013125 1.0000000000 1.1541461259
1.3333350000 1.0000000000 1.2952145904
1.6500020625 1.0000000000 1.4362830548
2.0000025000 1.0000000000 1.5773515192
0.0000000000 1.0000000000 0.0000000000
0.3432760191 1.0000000000 0.1716380095
0.4832092660 1.0000000000 0.2416046330
0.6783945480 1.0000000000 0.3391972740
0.8975798620 1.0000000000 0.4487899310
0.9895484809 1.0000000000 0.4947742405
0.9808319340 1.0000000000 0.4904159670
0.9082334193 1.0000000000 0.4541167096
0.7717489967 1.0000000000 0.3858744983
0.5940086165 1.0000000000 0.2970043083
0.3992760891 1.0000000000 0.1996380445
0.2067246684 1.0000000000 0.1033623342
0.0000000000 1.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
0.0000000000 0.0000000000 0.0000000000
why they didn't keep the order?
Rik
on 15 Aug 2019
Because Matlab is column based. The fprintf function goes through your matrix column by column, not row by row. It is an error that is easy to make (it even ended up in my master thesis).
The solution is to either transpose the matrix when you input it to fprintf, or to use the separate arrays (which you then shouldn't need to linearize).
fprintf(fileID,' %12.10f %12.10f %12.10f \r\n',XP_NODES,YP_NODES,ZP_NODES);

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