Subtract months from a given date in Matlab

I need to subtract 21 months from a gi开发者_JAVA百科ven date.

My solution as given below only takes me to the first month of the given year :(

[a,b,c]= datevec(date);
b= b-21;
datestr(datenum(a,b,c)) %--> 11-Jan-2011 (WRONG).

I want the answer to be 11-June-2009.

Go via date numbers rather than date vectors and use addtodate:

>> d = datenum(date);
>> e = addtodate(d, -21, 'month');
>> datestr(e)

ans =

11-Jun-2009