# making two different vectors the same length

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soloby on 13 Jun 2015
Commented: Walter Roberson on 13 Jun 2015
x1_lower = <1x100> vector
x2_lower = <1x110> vector
Im trying to plot (x1_lower+ x2_lower, y)
what's the best way of making them an equal length? or is there a way to get around this? thanks
soloby on 13 Jun 2015
Ok, let me ask a simpler question.
how do i add zeroes to the beginning or these end of the vectors to the same length as something like x = -10:.1:10

Walter Roberson on 13 Jun 2015
minlen = min(length(x1_lower), length(x2_lower));
plot(x1_lower(1:minlen) + x2_lower(1:minlen), y)
However I would in general expect that to fail as y would probably not be the same length.
The above code assumes that the two vectors are on the same origin and spacing, so the extra elements for x2_lower represent elements beyond the end of x1_lower and each element x1_lower(K) corresponds to x2_lower(K). If that is not the case then you need information about the origin and increments in order to align the two.
Walter Roberson on 13 Jun 2015
To pad with zeros at the end:
maxlen = max(length(x1_lower), length(x2_lower));
x1_lower(end+1:maxlen) = 0;
x2_lower(end+1:maxlen) = 0;
To pad with zeros at the beginning:
maxlen = max(length(x1_lower), length(x2_lower));
x1_lower = [zeros(1,maxlen - length(x1_lower)), x1_lower];
x2_lower = [zeros(1,maxlen - length(x2_lower)), x2_lower];
This code should work no matter which of the two is shorter.