Multiply values by the number of days in each month

Dear all,

I have a 41x35x360 array namely C. So the C has 360 pages; while 360 represents months from 1-1-1989 (to 12-31-2018 which is 360 months). I want to multiply the value inside each page to the number of days in each month (considering leap and non-leap years). If it is matter 41 and 35 are latitude and longitude, respectively.

C = rand(41,35,360) ;  % random 3d data 

For example:

C(41, 35, 1) * number of days in January 1989

C(41, 35, 2) * number of days in February 1989

...

C(41, 35, 360) * number of days in December 2018

Thank you

Answer 1

[Star Strider]

Use the eomday function to find the number of days in each month:

yearv = 1989:2018;
for k = 1:numel(yearv)
    daysInMonth(k,:) = [yearv(k), eomday(yearv(k), 1:12)];
end

This creates a matrix where the first column is the year and columns 2:13 are the days in each month of that year.

Adapt it to provide the information you need for your array.

Answer 2

[the cyclist]

C = rand(41,35,360) ;  % random 3d data

daysNonLeap = [31; 28; 31; 30; 31; 30; 31; 31; 30; 31; 30; 31];
daysLeap = daysNonLeap;
daysLeap(2) = 29;

daysFourYear = [daysNonLeap; daysNonLeap; daysNonLeap; daysLeap];

daysThirtyYear = [repmat(daysFourYear,7,1); daysNonLeap; daysNonLeap];

C = C .* permute(daysThirtyYear,[3 2 1]);