Read a file, store in variable.

This is the program I'm trying to create (very new to Matlab). I have the main program that is using airfoil geometry to calculate pressure distribution and use the pressure distribution later on in other equations.

So far: I have generated equation for NACA 4 and 5 series airfoil based on the input series number from the user. However, I want another option to have user generate their own x and y coordinates of the airfoil and I need to be able to use those values in the program.

    function [xs]=FSP()
    %closes all windows, clears everything
    writeofile=0;

    fprintf('\n');
    fprintf('Enter option: 1= 4 series, 2=5 series 3= upload');

    if ~nargin
        option = input ('\n select option:');
        if option ==1
            FourDigit=input('\n Type in NACA 4 series: ');
            alpha = input ('\n Type in angle of attack in degree: ');
        elseif option ==2
            FiveDigit= input('\n Type in NACA 5 series: ');
            alpha = input ('\n Type in angle of attack in degree: ');
        elseif option ==3
           %
           % 
        end 
    end
    N=100; % Number of points generated.

    if option == 1
        [x,y]= Airfoil4 (N,N,FourDigit);
    %    [xmid,ymid,Cp]=HessSmithPanel (x,y,alpha);
    %    [xU,yU,CpU]=UpperSurface (xmid,ymid,Cp,N);
    elseif option ==2 
           [x,y]= Airfoil5 (N,N,FiveDigit);
    %    [xmid,ymid,Cp]=HessSmithPanel (x,y,alpha);
    %    [xU,yU,CpU]=UpperSurface (xmid,ymid,Cp,N);
    elseif option ==3

    end

    figure
    plot (x,y);
    axis([-.1 1.1 -.4 .4]);

That is part of the main program that is currently working for 4 and 5 series, it gets the x and y coordinates in an array and plots them for future usage. I need the third option of data collection working similar to that.

This is an example of NACA 5 series

    function [x,y]=Airfoil5(nU,nL,NACA)
    xU=zeros(nU,1);
    cU=zeros(nU,1);
    dcU=zeros(nU,1);
    betaU=zeros(nU,1);
    xL=zeros(nL,1);
    cL=zeros(nL,1);
    dcL=zeros(nL,1);
    betaL=zeros(nL,1);

    L=floor(NACA/10000);
    P=floor(NACA/1000)-L*100;
    R=floor(NACA/100)-L*100-P*10;
    XX=NACA-L*10000-P*1000-R*100;

    maxt=XX/100;
    xf=P/20;
    Cli=3*L/20;
    %cmax=cmax*.01;
    %pcmax=pcmax*.1;
    %maxt=maxt*.01;

    syms m;
    sol=solve(xf==m*(1-sqrt(m/3)),m);
    m = double(real(sol(2)));

    Q=(3*m-7*m^2+8*m^3-4*m^4)/sqrt(m*(1-m))-3/2*(1-2*m)*(pi/2-asin(1-2*m));
    k1=6*Cli/Q;

    if R == 0
        for i=1:nU
            xU(i)=.5*(1-cos(pi*(i-1)/nU));
        end
        for i=1:nL
            xL(i)=.5*(1+cos(pi*(i-1)/nL));
        end

        tU=5*maxt*(.2969*sqrt(xU)-xU.*(.126+xU.*(.35372-xU.*(.2843-xU*.1015))));
        tL=5*maxt*(.2969*sqrt(xL)-xL.*(.126+xL.*(.35372-xL.*(.2843-xL*.1015))));

        for i=1:nU
            if xU(i)<m
                cU(i)=(k1/6)*(xU(i)*xU(i)*xU(i)-3*m*xU(i)*xU(i)+m^2*(3-m)*xU(i));
                dcU(i)=(k1/6)*(3*xU(i)*xU(i)-6*m*xU(i)+m^2*(3-m));
            else
                cU(i)=k1*m^3*(1-xU(i))/6;
                dcU(i)=-k1*m^3/6;
            end
            betaU=atan(dcU);
        end
        for i=1:nL
            if xL(i)<m
                cL(i)=(k1/6)*(xL(i)*xL(i)*xL(i)-3*m*xL(i)*xL(i)+m^2*(3-m)*xL(i));
                dcL(i)=(k1/6)*(3*xL(i)*xL(i)-6*m*xL(i)+m^2*(3-m));
            else
                cL(i)=k1*m^3*(1-xL(i))/6;
                dcL(i)=-k1*m^3/6;
            end
            betaL=atan(dcL);
        end
    else
        k2=(3*(0.217-.15)^2-0.217^3)/(1-0.217)^3;

        for i=1:nU
            xU(i)=.5*(1-cos(pi*(i-1)/nU));
        end
        for i=1:nL
            xL(i)=.5*(1+cos(pi*(i-1)/nL));
        end

        tU=5*maxt*(.2969*sqrt(xU)-xU.*(.126+xU.*(.35372-xU.*(.2843-xU*.1015))));
        tL=5*maxt*(.2969*sqrt(xL)-xL.*(.126+xL.*(.35372-xL.*(.2843-xL*.1015))));

        for i=1:nU
            if xU(i)<m
                cU(i)=(k1/6)*((xU(i)-m)^3-k2*(1-m)^3*xU(i)-m^3*xU(i)+m^3);
                dcU(i)=(k1/6)*(3*(xU(i)-m)^2-k2*(1-m)^3-m^3);
            else
                cU(i)=(k1/6)*(k2*(xU(i)-m)^3-k2*(1-m)^3*xU(i)-m^3*xU(i)+m^3);
                dcU(i)=(k1/6)*(3*k2*(xU(i)-m)^2-k2*(1-m)^3-m^3);
            end
            betaU=atan(dcU);
        end
        for i=1:nL
            if xL(i)<m

                cL(i)=(k1/6)*((xL(i)-m)^3-k2*(1-m)^3*xL(i)-m^3*xL(i)+m^3);
                dcL(i)=(k1/6)*(3*(xL(i)-m)^2-k2*(1-m)^3-m^3);
            else
                cL(i)=(k1/6)*(k2*(xL(i)-m)^3-k2*(1-m)^3*xL(i)-m^3*xL(i)+m^3);
                dcL(i)=(k1/6)*(3*k2*(xL(i)-m)^2-k2*(1-m)^3-m^3);        
            end
            betaL=atan(dcL);
        end
    end

    x=xL+tL.*sin(betaL);
    y=cL-tL.*cos(betaL);
    x=[x;xU-tU.*sin(betaU);x(1)];
    y=[y;cU+tU.*cos(betaU);y(1)];

So I need the third option to develop similarly like NACA 5 series and store the data from the text file into the variable x and y.

Here is the text file.

    AG19
         0.999992    0.000244
         0.994067    0.000848
         0.982082    0.002113
         0.968544    0.003504
         0.954708    0.004914
         0.940826    0.006276
         0.926943    0.007613
         0.913056    0.008933
         0.899168    0.010245
         0.885282    0.011547
         0.871396    0.012840
         0.857515    0.014123
         0.843633    0.015399
         0.829754    0.016658
         0.815876    0.017909
         0.801995    0.019144
         0.788118    0.020364
         0.774240    0.021567
         0.760358    0.022757
         0.746480    0.023934
         0.732598    0.025098
         0.718714    0.026246
         0.704832    0.027382
         0.690952    0.028505
         0.677070    0.029611
         0.663191    0.030702
         0.649316    0.031769
         0.635436    0.032803
         0.621559    0.033813
         0.607686    0.034792
         0.593811    0.035742
         0.579936    0.036661
         0.566066    0.037549
         0.552198    0.038403
         0.538328    0.039225
         0.524462    0.040010
         0.510601    0.040760
         0.496741    0.041474
         0.482880    0.042149
         0.469025    0.042788
         0.455177    0.043387
         0.441328    0.043948
         0.427484    0.044466
         0.413649    0.044946
         0.399815    0.045383
         0.385986    0.045776
         0.372169    0.046125
         0.358355    0.046428
         0.344545    0.046682
         0.330750    0.046887
         0.316965    0.047037
         0.303185    0.047134
         0.289421    0.047171
         0.275674    0.047146
         0.261933    0.047054
         0.248213    0.046888
         0.234514    0.046643
         0.220830    0.046310
         0.207177    0.045881
         0.193554    0.045344
         0.179962    0.044689
         0.166424    0.043904
         0.152931    0.042974
         0.139504    0.041884
         0.126159    0.040617
         0.112901    0.039151
         0.099774    0.037462
         0.086793    0.035521
         0.074020    0.033292
         0.061500    0.030726
         0.049351    0.027778
         0.037754    0.024395
         0.027090    0.020576
         0.018069    0.016536
         0.011377    0.012750
         0.006933    0.009581
         0.004065    0.007011
         0.002186    0.004880
         0.000960    0.003044
         0.000235    0.001406
         0.000001   -0.000094
         0.000368   -0.001552
         0.001471   -0.002908
         0.003259   -0.004084
         0.005777   -0.005206
         0.009368   -0.006368
         0.014713   -0.007619
         0.022632   -0.008896
         0.033028   -0.009988
         0.044948   -0.010773
         0.057612   -0.011265
         0.070626   -0.011515
         0.083847   -0.011575
         0.097208   -0.011488
         0.110664   -0.011286
         0.124193   -0.010995
         0.137773   -0.010634
         0.151402   -0.010216
         0.165062   -0.009753
         0.178754   -0.009253
         0.192471   -0.008724
         0.206209   -0.008174
         0.219965   -0.007607
         0.233740   -0.007028
         0.247527   -0.006440
         0.261333   -0.005847
         0.275149   -0.005250
         0.288979   -0.004652
         0.302827   -0.004054
         0.316687   -0.003459
         0.330560   -0.002868
         0.344449   -0.002282
         0.358351   -0.001705
         0.372267   -0.001137
         0.386195   -0.000582
         0.400136   -0.000039
         0.414079    0.000487
         0.428014    0.000997
         0.441936    0.001488
         0.455848    0.001958
         0.469754    0.002410
         0.483648    0.002838
         0.497536    0.003246
         0.511417    0.003632
         0.525297    0.003999
         0.539171    0.004338
         0.553041    0.004649
         0.566907    0.004932
         0.580771    0.005183
         0.594629    0.005404
         0.608483    0.005597
         0.622333    0.005758
         0.636177    0.005888
         0.650015    0.005989
         0.663852    0.006060
         0.677688    0.006098
         0.691521    0.006104
         0.705354    0.006082
         0.719189    0.006029
         0.733027    0.005945
         0.746863    0.005833
         0.760702    0.005691
         0.774544    0.005518
         0.788385    0.005316
         0.802230    0.005089
         0.816081    0.004833
         0.829932    0.004550
         0.843784    0.004242
         0.857640    0.003908
         0.871495    0.003551
         0.885353    0.003171
         0.899212    0.002768
         0.913070    0.002347
         0.926931    0.001903
         0.940790    0.001439
         0.954652    0.000956
         0.968488    0.000451
         0.982076   -0.000064
         0.994074   -0.000511
         1.000008   -0.000710

The text file generally contains the name of the airfoil and then the columns of x coordinate and y coordinate. I need to be able to take each of this coordinate and save them in the x and y variable like I have it in the airfoil5 function. I also need to have the N variable in the FSP funcction to be changed to the number of x-y coordinates that are coming in from the airfoil text file.

Any help would be greatly appreciated, Thank you.

Answer 1

[Walter Roberson]

Use textscan() with Headerlines 1 and format '%g%g'

[Kartavya]

Hi, I'm not familiar with that code but so far I have:

function [x,y]=AirfoilC

load Airfoil.dat;     %  read data into the my_xy matrix
x = Airfoil(:,1);     %  copy first column of my_xy into x
y = Airfoil(:,2);

and this works perfectly. The only thing I'm missing in this is that I need to be able to save the value of data that contains in Airfoil.txt file so I can use that information later on in the main program.