# how to compare two consecutive values in a matrix

14 views (last 30 days)
qing li on 29 Jul 2022
Commented: qing li on 31 Jul 2022
deal all,
how to compare two consecutive values in a matrix called 'temp' row-wise, the rule and the expecting result is as the following:
if first value>=second value , then bit=1;
else if first value<second value, then bit=0;
Store the bit generated every time in a matrix ‘M’.
This step will generate a matrix ‘M’ (logical) of size same a temp.
say for instance let's say matrix 'temp' be temp=[1,2,2,1;3,4,4,3;5,6,6,5;7,8,8,7]
can anyone give me some hints, thx a lot !

Voss on 29 Jul 2022
temp=[1,2,2,1;3,4,4,3;5,6,6,5;7,8,8,7]
temp = 4×4
1 2 2 1 3 4 4 3 5 6 6 5 7 8 8 7
In each row, you have one fewer comparisons than you have elements, so M is of size one less than temp.
M = logical(temp(:,1:end-1) >= temp(:,2:end))
M = 4×3 logical array
0 1 1 0 1 1 0 1 1 0 1 1
Maybe you want to append a column of false values to M.
M(:,end+1) = false
M = 4×4 logical array
0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0
Another way to do the same:
temp2 = [temp NaN(size(temp,1),1)];
M = logical(temp2(:,1:end-1) >= temp2(:,2:end))
M = 4×4 logical array
0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0
qing li on 31 Jul 2022
great that is what i want ！ thank you sooo much sir ！ that is really helpful !

Matt J on 29 Jul 2022
M=(diff(temp2,1,2)<=0);
qing li on 29 Jul 2022
thank you so much sir ! That is really helpful !