Question

I have written a function in MATLAB but it will not return my outputs. It returns the first output as ans=a # but that’s it. I thought function[argout1,argout2,...argoutn=funcname(in1,in2,...inn) returns all outputs in the format argout1= a #, argout2= a # and so on.

I realize I could use disp() or some other built in function but what is the point in all that when you have a function file. The function is accessing the inputs from an excel spreadsheet but I didn’t think that should make a difference. Any help would be greatly appreciated.

The code is as follows.

function[y_int1, y_int2, Youngs_Modulus, Poissons_Ratio, Youngs_Modulus_Percent_diff, Poissons_Ratio_Percent_diff, RMS1, RMS2]= Lab3_EC(elong1,elong2,elat1,elat2,thick,width,load,N)



%average longitudinal strain
avgLongs=((elong1)+(elong2))/2;



%average lateral strain
avgLats=((elat1)+(elat2))/2;


%Find's the area of the sample

A=thick*width;


%Finds the applied stress
stress=load./A;


%declares a variable x1 for Long Strain
x1=avgLongs;


%declares a variable y1 for Applied Stress
y1=stress;

%Declares variables to compute slope1

x1bar=mean(x1);
y1bar=mean(y1);
sxy1=sum(x1.*y1);
sx1=sum(x1);
sy1=sum(y1);
sx1s=sum(x1.*x1);
sx11s=(sum(x1))^2;
slope1=(N*sxy1-sx1*sy1)/(N*sx1s-sx11s);
y_int1=y1bar-slope1*x1bar;

%x points
xp=linspace(min(x1),max(x1));

% y points
yp1=slope1*xp+y_int1;

%Declares variables to compute slope 2

%Since our second calculation of linear regression uses Average
%Longitudinal Stress we can re-use the variable x1 

y2=abs(avgLats);
y2bar=mean(y2);
sxy2=sum(x1.*y2);
sy2=sum(y2);
slope2=(N*sxy2-sx1*sy2)/(N*sx1s-sx11s);
y_int2=y2bar-slope2*x1bar;


%y points
yp2=slope2*xp+y_int2;


%preallocate space for error1 vector
Error1=zeros(N,1);

%compute error1
for i=1:N;
   Error1(i)= (stress(i)-y_int1-slope1*avgLongs(i))^2;
end
Error1=sum(Error1(5));   

%preallocate space for error2 vector

Error2=zeros(N,1);
for i=1:N;
    Error2(i)=(abs(avgLats(i))-y_int2-slope2*avgLongs(i))^2;
end
Error2=sum(Error2(5));

RMS1=sqrt(Error1/N);

RMS2=sqrt(Error2/N);


Lab_2_E=(stress(5)-stress(1))/(avgLongs(5)-avgLongs(1));
Lab_2_v=(abs(avgLats(5)-avgLats(1))/(avgLongs(5)-avgLongs(1)));
Youngs_Modulus=slope1;
Poissons_Ratio=slope2;
Youngs_Modulus_Percent_diff=((abs(Youngs_Modulus-Lab_2_E))/Lab_2_E)*100;
Poissons_Ratio_Percent_diff=((abs(Poissons_Ratio-Lab_2_v))/Lab_2_v)*100;



%Plot stress strain diagram and poisson's ratio
figure(1), plot(avgLongs,stress,'k',x1,y1,'o',xp,yp1,':g'),hold on,...
    xlabel('Long Strain(in/in)'),ylabel('Stress(psi)'),...
    title('Stress vs. Long Strain'), legend('Exp','data points','Calc',...
    'Location','SouthEast')
figure(2),plot(avgLongs,abs(avgLats),x1,y2,'+',xp,yp2,'-- m'),hold on,...
    xlabel('Long Strain(in/in)'),ylabel('Lat Strain(in/in)'),...
    title('Poisson''s Ratio'),legend('Exp','data points','Calc',...
    'Location','SouthEast')

Answer 1

Assume you have a function fun:

[o1, o2, o3, o4, o5] = fun(i1, i2, i3, i4);

If you execute

fun(in1, in2, in3)

there is only one output argument: ans the default output argument. This’ll get the value of the first output argument defined in your function header (namely o1).

If you want more outputs, you have to specify them:

[out1, out2, out3] = fun(in1, in2, in3);

Now out1, out2 and out3 will respectively contain the values assigned in the function to o1, o2 and o3.

You should definitely read through function documentation.