How i Calculate the average number of even numbers in an array?

How i Calculate the average number of even numbers in an array?

If the array:

1.3700    1.2200    2.2000    2.2800

so the avarage:

1.9

because: (1.22+2.22+2.28)/3=1.9

How i do this?

[KSSV]

Check your question properly....

(1.22+2.22+2.28)/3 = 1.90...

What do you mean by odd numbers here in the array?

Answer 1

[Bruno Luong]

a = [1.3700    1.2200    2.2000    2.2800];
ac = round(a*100);
mean(ac(mod(ac,2)==0))/100

result

ans =

    1.9000

[madhan ravi]

I thought of the same solution but didn't know to use round properly there ;-)

>>a=sprintf('%.32f\n',a.*100)

a =

    '137.00000000000000000000000000000000
     122.00000000000000000000000000000000
     220.00000000000002842170943040400743
     227.99999999999997157829056959599257
     '

[Bruno Luong]

Here is what might happen if one does't take care about rounding

mod(1.12*100,2)==0

ans =

  logical

   0

[madhan ravi]

Exactly!

Answer 2

[Kevin Chng]

My answer is

Check the index of Even number first

a = [1.3700    1.2200    2.2000    2.2800];
index = mod(single(a*100),2)==0;

Calculate the mean value of Even Number in the array

mean(a(index))

[tomer kapuri]

thank you!!!

more question...how i can sum ther counter of even numbers?

[Kevin Chng]

How to get the counter of even numbers? You may try

nume1(index)

or

sum(index)

[Bruno Luong]

sum is correct numel is not

[tomer kapuri]

is not working...

[Kevin Chng]

Ya, numel is calculating the number of element. Sorry for my mistake.

However, tomer kapuri, any difficulties you are facing since you say something is not working.

Answer 3

[GT]

Hi Tomer,

I am not sure if I understand your question correctly.

In MATLAB to calculate the average you would use the function: mean

In your example:

a = [1.37    1.22    2.20    2.28];
yourAverage = mean(a)

Please note in your question you asked about odd number. You could do:

mean(a(2:end))

This is adding the last 3 elements of the array a, and dividing by 3 as you illustrated, but there is something not right with your Maths... as:

(1.22+2.22+2.28)/3 is not 4.2.

Hope this helps.