Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

So basically I'm trying to run this project, and it doesn't work for me, shows error, but with other code, and similar program it works. Help me out please, I dont understand whats wrong (btw it's not fully written program, but still Im getting that error.)

Unable to perform assignment because the indices on the left side are not compatible with the size of the

right side.

Error in untitled5 (line 9)
av(i)=fa(xv,d(i));

x0=input ('Input x0:');
xn=input ('Input xn:');
xh=input ('Input xh:');
d=input ('Input d:');
e=input ('Input e:');
xv=x0:xh:xn;
[m,n]=size(xv);
for i=1:n
    av(i)=fa(xv,d(i));
end
for i=1:n
    bv(i)=fb(x,av(i));
end
for i=1:n
    cv(i)=fc(a,b,ev(i));
end

[Geoff Hayes]

@Haroldas Vaitiekus - are fa, fb, and fc functions? If so, what do they return - scalars or arrays? Please clarify.

[Haroldas Vaitiekus]

Yes, they are functions, this is the fc, same with fb and fa

function [c] = fc(a,b,e)

if (a>b)

c=5*a*sin(4*b);

else (a<=b)

cos(e.^a);

end

[Geoff Hayes]

@Haroldas Vaitiekus - since

av(i)=fa(xv,d(i));

and xv is an array, then the output of each of your functions will be an array as well. Is this the intent? Do you mean for each of these functions to return arrays?

[Haroldas Vaitiekus]

1. Calculate the values ​​of the functions a, b, and c as x varies in the interval [x0, xn] in steps hx. Sketch the graph of the function a.

That is my assignment

[Walter Roberson]

else (a<=b)
  cos(e.^a);
end

that calculates a<=b and displays the result. Then it calculates the cos and discards the result, and does not assign to c

[Haroldas Vaitiekus]

So I just need to make it

else (a<=b)

c = cos(e.^a);

end

?

If so, I'm still getting same error, and I'm stuck at fa which is kinda simple one:

function a = fa (d,x)

a = d*(x.^2)-(2*abs(x))-3;

end

[Walter Roberson]

In MATLAB

else (a<=b)
    c = cos(e.^a);

is equivalent to

else
    (a<=b)
    c = cos(e.^a);

Do not follow "else" with a condition.

If you want the else branch to be selectively executed then

elseif (a<=b)
    c = cos(e.^a);

You should then be asking yourself under what circumstances could both a>b and a<=b be false that you might want to execute the branch selectively. The answer to that question is both would be false if a or b are nan. Or both could be false if a or b are non-scalar.

Answer 1

[David Hill]

x0=0;
xn=10;
xh=.1;
d=3;
xv=x0:xh:xn;
av=fa(xv,d);
plot(xv,av)

AV=@(xv,d)d*(xv.^2)-(2*abs(xv))-3;%with a simple function you might just want to make an anonymous function
plot(xv,AV(xv,d))

function a = fa (x,d)
   a = d*(x.^2)-(2*abs(x))-3;
end