# How to flip a signal ?

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Tomaszzz on 7 Mar 2022
Answered: Mathieu NOE on 7 Mar 2022
Hi all,
I have an acceleration signal during human walking (walk forward, turn around, walk back).
The attached is the 24x1 cell containing arrays of dimensions 100x 1 and each of these respresent acceleration signal between certain indices in the signal. Each array is plotted over the figure below. When the subjects turns around, it seems the signal is flipped around resulting in a half of the arrays being a negative mirror image of the remaining half of the arrays.
This is more visible if a plot first 12 arrays and second 12 arrays on seperate figures:
%Plot each array
figure
hold on
for i = 1:12
plot(P_acc_y_cycle{i},'r');
end
figure
hold on
for i = 13:24
plot(P_acc_y_cycle{i},'r') ;
end How can I flip the first part (first 12 arrays) so it resembles the second part?

Mathieu NOE on 7 Mar 2022
hello
you simply apply a negative gain = -1 to your data you want vertical flipped
%Plot each array
figure
hold on
for i = 1:12
plot(-P_acc_y_cycle{i},'r'); % here negative gain = -1
end
for i = 13:24
plot(P_acc_y_cycle{i},'b') ;
end David Hill on 7 Mar 2022
plot(abs(P_acc_y_cycle{i}-10)-10,'r') ;