make nested for loop output a matrix and other error

Hello again turns out i asked the wrong question.

I am writing a code that compares the values of X to each in A, then running them through an equation. right now it outputs a matrix of columns [A, B, X, deflection] I want it to be a matrix of hight A (so row one is A(1) and so on) and length X (so column 1 is X(1)). therefor output(1,1) should be the deflection if A(1) and X(1) are plugged into an equation.

another problem I have is that when i change z to 1000 I get an error

"Array indices must be positive integers or logical values.

Error in bridge_start (line 55)

if a(i) > x(j)"

in the end i need A and X to each have 1000 point in them.

%get inputs first
E = 1.75*10^6 ;  %lbf/in^2
I = 175        ; %in^4
L = 4;
p = 50;
equation1 = @(b,x) -((p.*b.*x)./(6*L*E*I)).*(L^2 -b.^2 - x.^2);
equation2 = @(a,b,x) -((p.*b.*x)./(6*L*E*I)).*(L^2 -b.^2 - x.^2)-((p.*(x-a).^3)./(6*E*I));
z = 4
[a,x]=deal(linspace(1,L,z))
b=L-a

%find data for subplot1
%one curve, max vs a

%outer loop
for i = linspace(1,L,z)
    %inner loop
    for j = linspace(1,L,z)
        if a(i) > x(j)
            deflection = equation1(b(i),x(j))
        else
            deflection = equation2(a(i),b(i),x(j))
        end
        row = sub2ind([4,4], a(j),x(i))
        output(row, :) = [a(i),b(i),x(j), deflection  ]
    end
end

thank you all for the help. there seems to be a bit of a learning curve to Matlab

Answer 1

[KALYAN ACHARJYA]

First One:

The question seems easy, but I did not undestand it exactly, sorry

Second one:

another problem I have is that when i change z to 1000 I get an error

"Array indices must be positive integers or logical values.

Say, as per your code-

>> L=4;
>> z=1000;
>> i=linspace(1,L,z)
i =
  Columns 1 through 13

    1.0000    1.0030    1.0060    1.0090    1.0120    1.0150    1......so on

Now if you want to acess a(i), its invalid, because of decimal, to access array indexing values must be interger and positive

When you consider z=4

then i having length of 1

>> i
i =
     4
>> j
j =
     4
>> 

Please ensure the integer values of i and j, to ensure to avoid this error

>> i=linspace(1,z,L)
i =
           1         334         667        1000

Or

>> i=1:L:z
i =
  Columns 1 through 22
     1     5     9    13    17    21    25    29    33    37    41    45 ...so on

Hope this helps for 2nd question.

[Jackson Perrelli]

thank you very much, also wi wash able to figure out the first question.

%get inputs first
E = 1.75*10^6 ;  %lbf/in^2
I = 175        ; %in^4
L = 4;
p = 50;
equation1 = @(b,x) -((p.*b.*x)./(6*L*E*I)).*(L^2 -b.^2 - x.^2);
equation2 = @(a,b,x) -((p.*b.*x)./(6*L*E*I)).*(L^2 -b.^2 - x.^2)-((p.*(x-a).^3)./(6*E*I));
z = 4;
[a,x]=deal(linspace(1,L,z));
b=L-a;
results = zeros(z,z) ;
output = zeros(1,z);


%find data for subplot1
%one curve, max vs a

%outer loop
for i = 1:z
    %inner loop
    for j = 1:z
        if a(i) >= x(j)
            deflection = equation1(b(i),x(j))
        else
            deflection = equation2(a(i),b(i),x(j))
        end
        results(i,j) = deflection
        deflection = results
    end
end

this is what i ended up with and it seems to work alright. would you happen to know a more efficient way to rewrite this because it takes a hot min to calculate for 1000 points