I want to find minimum values from an array?.

Min(x) simply gives the most smaller value but i dont want this i want atleast 2 min values and by taking those values i have to calculate the distance. In attached image i have calculated the local minima values and its location. now what i have to do is MATLAB search the minimas array and then locate min values for me. Values for minimas and locs are: Minimas =

-86.5647
-80.3647
-81.3588
-106.9882
-77.0765
-77.8235
-92.2353
-106.2235
-115.3118
-98.3706

locs =

    30
    34
    36
    50
    93
    97
   110
   121
   127
   136

Answer 1

[Star Strider]

I would use the sort function with two outputs:

[x_sort,idx] = sort(x);

and take the first two values of each output vector, since the default behaviour of sort is to go from lowest to highest.

[Usman]

can you please tell me how this actually works? as i am new to matlab so have no idea? because [x_sort,idx] = sort(x); arrange the values in descending order eg: Minimas=[5 7 6 9] then after execution it becomes sort_x = [5 6 7 9] and my scenraion is i have to extract 5 and 7 as min value? any suggestion

[Star Strider]

Since you want only the first two values and ‘x_sort’ and ‘idx’ are column vectors:

Result = [x_sort(1:2) idx(1:2)]

will contain the two lowest values and their indices in the vector.

If they are row vectors:

Result = [x_sort(1:2); idx(1:2)]'

[Usman]

ok thankyou strider. I got the idea. but i want MATLAB to extract those minimum values autmatically. so i dont have to look up what are those and then tell to extract.

[Star Strider]

My pleasure.

It is doing this automatically. If you want to create a function that will only return the lowest two values in a vector, save this code separately as its own .m file as: min2.m:

function lowest_two = min2(x)
% MIN2 Returns the lowest two values in a vector as
%      a 2x2 array with the values in the first column 
%      and their indices in the second column.  

x = x(:);                         % Create Column Vector
[v,ix] = sort(x);                 % Sort Ascending
lowest_two = [v(1:2)  ix(1:2)];   % Return Lowest Two Values And Their Indices
end

Then call it in your code as:

lowest2 = min2(x);