What is the best way to flip part of the graph about the x axis in MATLAB ?

so as stated above when I am trying to plot a graph of a wave, I want to reflect the down dips in the graph to be upwards, is there anyway of doing that directly?

[Ameer Hamza]

Can you show the shape of the graph?

[Abdullah AlQulaibi]

as you can see the noted valley are 2 different forces that have to be added which means that they should be inverted about the red line shown as well.

Answer 1

[Star Strider]

Multiply the y-values by -1 to ‘flip’ it. This is the best way, and one you can use with the findpeaks function to determine the ‘peaks’ from the original data and the ‘valleys’ from the inverted data.

You may want to add an offset if you want it completely above or below y=0.

[Star Strider]

Abdullah AlQulaibi’s Answer moved here —

thank you for your reply, will that help with flipping the points shown in the figure here?

[Star Strider]

My pleasure.

To flip them about the red line (at y=1), first subtract 1 from your signal, then multiply it by -1, then add 1 to it.

If you want everything to be above the red line at y=1, subtract 1 from your signal, then take the absolute value (the abs function), and add 1 back to it.

If ‘y’ is your signal:

y_new = 1 + abs(y - 1);

One of these should do what you want.

Answer 2

[Ameer Hamza]

Since you want to invert about y=1 line, you can change the y variable of your data like this,

yInverted = -y+2; % +2 to bring it back to +1 after inversion
ploy(x, yInverted);