Question

(a) A cantilever beam shown in Figure 6 is subjected to a concentrated load P. Deflection of the beam at each point can be defined by the following equations: 6EI Pa 6EI F3x-a) for axx<l The following MATLAB code calculates and plots the deflection diagram for a beam with 1-4 m, d1 = 3 m, b = 1 m,E>210 x 10, Pa, 1 = 285 x 10-6 m4 and P = 20 kN. Find at least FOUR errors in the code. For each error identified, explain why the error is caused. Figure 6 clear, clc L-4: a-3: b-1i E-210E9 I-285E-6; P=2083; x-0,0.01,L for i-1length (x) elseif end plot (x,y) (8 marks)

Answer 1

Here is the given code:

clear,clc;

L=4;

a=3;

b=1;

E=210E9;

I=285E-6;

P=20E3;

X=0,0.01,L;

for i==1:length(X);

if X(i)<a

Y(i)=p*(x(i).^2).*(3*a-X(i))./(6*E*I);

elseif

Y(i)=p*(a^2)*(3*X(i)-a)./(6*E*I);

end

plot(X,Y)

These are the errors in the code:

1)X=0,0.1,L

But it gives error.

Because X has to be given values in the range 0 to L with increment 0.1.but it cann't.so corret syntax for it is   X=0:0.1:L.

2) for i==1:length(X)

But it gives error.

Because i==1 is used for equlity condition not for the assignmet to the range.

so correct syntax is for i=1:length(X)

3)

elseif

Y(i)=p*(a^2)*(3*X(i)-a)./(6*E*I);

But it gives error.

Because, elseif always require a condition to execute the statement.so here we se the correct control statement is else.

else

Y(i)=p*(a^2)*(3*X(i)-a)./(6*E*I);

4)

for i==1:length(X)

if X(i)<a

Y(i)=p*(x(i).^2).*(3*a-X(i))./(6*E*I);

else

Y(i)=p*(a^2)*(3*X(i)-a)./(6*E*I);

end

But it gives error.

Because we have end the for loop.but here we cant end the for loop.so we end after the for loop.

correct syntax is :

for i=1:length(X)

if X(i)<a

Y=p*(x(i)^2).*(3*a-X(i))./(6*E*I);

else

Y=p*(a^2)*(3*X(i)-a)./(6*E*I);

end

end

5) Y(i)=p*(x(i)^2).*(3*a-X(i))./(6*E*I);

here Y(i) is not required.so we use only Y.correct syntax is Y=p*(x(i)^2).*(3*a-X(i))./(6*E*I);