How do i retrieve a specific value from a 2D matrix?

Hello,

I've a matrix from which I want to get a specific value based on earlier calculations. So I want the value of B matched with A based on earlier calculated values (Thus the value of B which belongs to A)

earliercalculatedvalue = value from a certain function

if true
A = [0, 2.5, 5, 7.5, 10, 12.5, 13.5, 15];                                                                                  
B = [0.0433512251001877, 0.043577394493621, 0.0439878459898567, 0.044652541077113, 0.0450839697675535, 0.0458295673490097, 0.0461248505159152, 0.0465317879404617];
Matrix = [A;B];
Wantedvalue=Matrix(A==earliercalculatedvalue,:);
end

Thanks very much in advance!

[Adam]

And what is wrong with your code specifically? What are you getting as Wantedvalue?

[David van Nederpelt]

I want the value of B where A=earliercalculatedvalue. For the wantedvalue i'm getting a 1D array but I want just the value of B belonging to A (for example the earlier calculated value=5 then the Wantedvalue should be: 0.0439878459898567)

Answer 1

[Star Strider]

One approach:

earliercalculatedvalue = 5;

Wantedvalue = B(A == earliercalculatedvalue)                                % Simplest
Wantedvalue = interp1(A, B, earliercalculatedvalue,'linear','extrap')       % More Robust

give the same result for both:

Wantedvalue =
   0.043987845989857

Wantedvalue =
   0.043987845989857

Answer 2

[Honglei Chen]

You can use

B(A==earliercalculatedvalue)

HTH