MATLAB: Matlab should have give array but it gives a number. How to fix

arrayMATLAB

I have a code to calculate some lambda values then uses these values with our r values to find d values. However, these values are 1×21 array but the given answer is just a number why? and how to fix this?
U=[10 9.7 9.4 9.1 8.8 8.5 8.2 7.9 7.6 7.3 7.0 6.7 6.4 6.1 5.8 5.5 5.2 4.9 4.6 4.3 4.0];
h=6.625.*10.^(-34);
m=9.109.*10.^(-31);
e=1.602.*10.^(-19);
lambda=h./sqrt(2.*m.*e.*U.*1000);
R=65.*10.^(-3);
r1i=[0.7 0.75 0.8 0.85 0.9 0.9 1.05 1.05 1.1 1.1 1.1 1.15 1.15 1.10 1.10 1.10 1.10 1.15 1.10 1.15 1.2];
r1o=[1.2 1.3 1.35 1.4 1.4 1.45 1.5 1.55 1.55 1.6 1.6 1.67 1.67 1.75 1.75 1.8 1.9 1.9 2 2.05 2.1];
r2i=[0.75 0.75 0.85 0.95 1 1 1.05 1.1 1.1 1.1 1.1 1.15 1.2 1.2 1.25 1.25 1.25 1.3 1.3 1.3 1.35];
r2o=[1.25 1.3 1.4 1.4 1.45 1.45 1.5 1.55 1.6 1.65 1.65 1.7 1.7 1.75 1.85 1.9 1.9 1.95 2 2.05 2.1];
r3i=[0.7 0.75 0.75 0.8 0.85 0.85 0.9 0.95 1 1 1 1 1.05 1.05 1.05 1.1 1.1 1.15 1.15 1.15 1.2];
r3o=[1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.5 1.55 1.6 1.6 1.65 1.7 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05];
d1i=(2*R.*lambda)/(10.^(-2).*r1i);
d1o=(2*R.*lambda)/(10.^(-2).*r1o);
d2i=(2*R.*lambda)/(10.^(-2).*r2i);
d2o=(2*R.*lambda)/(10.^(-2).*r2o);
d3i=(2*R.*lambda)/(10.^(-2).*r3i);
d3o=(2*R.*lambda)/(10.^(-2).*r3o);
dinner=(d1i+d2i+d3i)/3
douter=(d1o+d2o+d3o)/3

Best Answer

Use the elementwise division:
d1i=(2*R.*lambda) ./ (10.^(-2).*r1i);
%                 ^
You have used the elementwise operations exhaustively, even if they are not needed, because the operands are scalars only. But at the only location, where it is needed, the matrix division / is applied. I'd use:
d1i = 2 * R * lambda ./ (1e-2 * r1i);
% or even nicer:
d1i = 200 * R * lambda ./ r1i;
By the way, compare
h=6.625.*10.^(-34);
with
h = 6.625e-34;
The first is an expensive power operation, while the second is a cheap constant - and nicer. Then your code becomes:
U = [10 9.7 9.4 9.1 8.8 8.5 8.2 7.9 7.6 7.3 7.0 6.7 6.4 6.1 5.8 5.5 5.2 4.9 4.6 4.3 4.0];
h = 6.625e-34;
m = 9.109e-31;
e = 1.602e-19;
lambda = h ./ sqrt(2 * m * e * U * 1000);
R = 65e-3;
ri = [0.7 0.75 0.8 0.85 0.9 0.9 1.05 1.05 1.1 1.1 1.1 1.15 1.15 1.10 1.10 1.10 1.10 1.15 1.10 1.15 1.2; ...
      0.75 0.75 0.85 0.95 1 1 1.05 1.1 1.1 1.1 1.1 1.15 1.2 1.2 1.25 1.25 1.25 1.3 1.3 1.3 1.35; ...
      0.7 0.75 0.75 0.8 0.85 0.85 0.9 0.95 1 1 1 1 1.05 1.05 1.05 1.1 1.1 1.15 1.15 1.15 1.2];
ro = [1.2 1.3 1.35 1.4 1.4 1.45 1.5 1.55 1.55 1.6 1.6 1.67 1.67 1.75 1.75 1.8 1.9 1.9 2 2.05 2.1; ...
     1.25 1.3 1.4 1.4 1.45 1.45 1.5 1.55 1.6 1.65 1.65 1.7 1.7 1.75 1.85 1.9 1.9 1.95 2 2.05 2.1; ...
     1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.5 1.55 1.6 1.6 1.65 1.7 1.7 1.75 1.8 1.85 1.9 1.95 2 2.05];
di = 200 * R * lambda ./ ri;   % Auto-expand, >= R2016b

do = 200 * R * lambda ./ ro;   % Auto-expand, >= R2016b
dinner = mean(di, 1)
douter = mean(do, 1)
Less chances for typos.
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