calculation of time series.

I have monthly (420 months) time series data of temperature . I need to calculate a another time series based on following formula:

x = T(month,i) - T(month,i-1)

where, T(month,i) is temperature of current month

T(month,i-1) is temperature of previous month

how to create a time series of x ?

Answer 1

[Thorsten]

 diffdata = diff(ts.Data)
 difftime = ts.Time(1:end-1)+diff(ts.Time)/2;
 tsdiff = timeseries(diffdata, difftime)

Answer 2

[Image Analyst]

If the second index is the month number, what does the first index represent? Have you tried

x = diff(T(month,:))?

[SONI SONI]

both represents month. month,i is number of month. we can write x = T(i) - T(i-1)

suppose i is current month (January) and i-1 is previous month (December)

[Image Analyst]

But originally you said T was a 2-D array - it had two indexes: for a row and a column. Now you're saying T is a 1D array taking only one index. Totally inconsistent. Which is it?????

Answer 3

[SONI SONI]

Temperature is 2-D array. I am trying to say I have a arrays T (time series of temperature January to December 1*12). now I want to substrate temperature values from current month to previous month. for example feb - jan, mar - feb....

But I have solved this problem

x(i) = T(i) - T(i-1)

[Image Analyst]

Now you're back to a 1-D array, NOT a 2-D array despite what you say, because it has only 1 index.

And your code just does diff() which is the same as what I gave you except in a function instead of a for loop.

I give up.

[SONI SONI]

Thank you sir, for the interest to help me.