Writing a function that merges two sorted vectors

Hello, I need to write a function that merge two sorted vectors to one sorted vector that containes all the values.

My code is:

vec1= input('enter vec1\n');

vec2= input('enter vec2\n');

vec1=sort(vec1)

vec2=sort(vec2)

function [res]=merge(vec1, vec2)

n1=length(vec1);

n2=length(vec2);

n=n1+n2;

res=zeros(n, 1);

if n1==0

res=vec2;

elseif n2==0

res=vec1; else

 i1=1;

 i2=1;

end

for j=1:n

if i1>n1

res(j)=vec2(i2);

i2=i2+1;

elseif i2>n2 res(j)=vec(i1); i1=i1+1;

 elseif  vec(i1)<vec(i2)
        res(j)=vec(i1);
        i1=i1+1;
    else
        res(j)=vec2(i2);
        i2=i2+1;
    end
end
end

My questions are: Is my code right and how can I call the new function that I created? (I saved the file named 'merge' in a function file).

[Ameer Hamza]

First of all, you should format your code properly: https://www.mathworks.com/matlabcentral/answers/7885-tutorial-how-to-format-your-question so that others can easily read it.

There are some mistakes in your merge function. You are using vec on some lines instead of vec1 or vec2, so it is difficult for me to understand what do mean by merging two sorted vectors. Still, I have tried to answer this question according to my understanding of this code. You can see it in answer section below.

Answer 1

[Ameer Hamza]

If you simply want to join two sorted vectors you can use

new_vec = [vec1 vec2];

but this seems improbable to me since joining two sorted vectors like this may not be very useful. The second possibility is, you also want to sort the result, you can do that as

new_vec = sort([vec1 vec2]);

In this second case, you don't even need to run

vec1=sort(vec1)
vec2=sort(vec2)

because the command I mentioned will sort both of them together.

In either case, no need to write your own merge function. You can use MATLAB builtin function to reach same results.

[Lee Cohen]

Thank you for the answer, I know this Matlab function, but my task is to write a new function that merges those vectors. Here is my fixed code:

vec1= input('enter vec1\n');

vec2= input('enter vec2\n');

vec1=sort(vec1)

vec2=sort(vec2)

function [res]=merge(vec1, vec2)

n1=length(vec1);

n2=length(vec2);

n=n1+n2;

res=zeros(n, 1);

if n1==0

res=vec2;

elseif n2==0

res=vec1; else

 i1=1;

 i2=1;

end

for j=1:n

if i1>n1

res(j)=vec2(i2);

i2=i2+1;

elseif i2>n2

res(j)=vec1(i1);

i1=i1+1;

 elseif  vec1(i1)<vec2(i2)
        res(j)=vec1(i1);
        i1=i1+1;
    else
        res(j)=vec2(i2);
        i2=i2+1;
    end
end
end

I would like to know if there is somthing wrong with it.

[Ameer Hamza]

Yes, Your function is giving correct output. You can just try by calling the function like this

merged_vector = merge(vec1, vec2);

You can add this line before the definition of the function merge.