can someone help me create function with 2 inputs that creates a single output?

I have been asked to create the following:

Create a function called Ex7b with 2 inputs (n and m) and a single output. Write the function so the output is the sum of the sets of n numbers between 1 and m. for example if n=4 and m=100:

?????? = [1 + 2 + 3 + 4 5 + 6 + 8 + 9......97 + 98 + 99 + 100]. The function should round m to the nearest multiple of n.

I have looked at all the info on creating functions, but have no idea on where to start with this one.

Thanks

Answer 1

[Stephan]

Hi,

start reading here and work through the examples given:

https://de.mathworks.com/help/matlab/ref/function.html

Best regards

Stephan

[Sam Thorpe]

Hi Stephan,

I understand the underlying concepts around creating functions, what I'm struggling with here is seperating the values in the array so I can add them together.

I have tried specifying output as 1:n:m as to start at 1 and count up in values of n until it reached the mth term, but this just skips every nth value and returns the sum of the lot.

[Stephan]

Try to understand what happens:

m = 100
n = 4
result  = sum(reshape(1:m,n,[]),1)

Therefore:

• think about what 1:m does
• read about reshape --> reshape(x,m,n)
• and check how this sum works - meant is input argument '1' --> sum(x,1)

[Sam Thorpe]

Thank you for your help Stephan. After a bit of logical thinking and your tips, I have gotten the function to work exactly as I wanted.

function ex7b=sumset(n,m)
o=n*ceil(m/n) %round the array up to nearest multiplication of n
p=[1:o] %definition of the array
q=(numel(p))/n %calculation of column size
x=reshape(p,[n,q]) %reshaping the array in to an n by m/n array
y=x.' %transposition of array
z=sum(y) %sum of each array row
end

[Stephan]

Nice to hear