Why between(datetime1, datetime2) is different from (-1)*between(datetime2, datetime1)?
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I am trying to measure the number of 'quarters' apart, between a single datetime r, and a vector of datetimes v. Could somebody please explain why Q1 & Q2 are different?
r = datetime(1991,6,30,'Format','dd/MM/yyyy');
v = dateshift(datetime(1990,12,31,'Format','dd/MM/yyyy'),'end','quarter',0:5);
%CASE 1
dif = between(r, v, 'quarters')
Q1 = split(dif, 'quarters')
%CASE 2
dif = between(v, r, 'quarters')
Q2 = (-1)*split(dif, 'quarters')
1 Comment
the cyclist
on 4 Mar 2024
Edited: the cyclist
on 4 Mar 2024
A distilled version of the question is, why is there a "magnitude" difference between the outputs below? It is admittedly counter-intuitive.
dt1 = datetime("30/06/1991","Format",'dd/MM/yyyy');
dt2 = datetime("31/12/1990","Format",'dd/MM/yyyy');
between(dt1,dt2)
between(dt2,dt1)
Answers (1)
Voss
on 4 Mar 2024
Moved: Dyuman Joshi
on 5 Mar 2024
"In general, t2 is not equal to t1 + dt, unless you include 'time' in components."
3 Comments
Dyuman Joshi
on 5 Mar 2024
r = datetime(1991,6,30,'Format','dd/MM/yyyy')
v = dateshift(datetime(1990,12,31,'Format','dd/MM/yyyy'),'end','quarter',0:5)
The difference is not symmetric/identical for every time component -
str = {'years','quarters','months','weeks','days' };
for k=1:numel(str)
disp(str{k})
disp('CASE 1')
disp(between(r, v, str{k}))
disp('CASE 2')
disp(between(v, r, str{k}))
disp(' ')
end
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