I am trying to find the maximum and minimum values from a given set of data.

when I am using findpeaks command in Matlab I am only getting the peak value I also want the minimum value could you suggest which command I can use.I am also attaching the data file which includes one column of time and one column of stress signals.I have also attach the Matlab file,please find the attachment

Answer 1

[Pedro Galvez]

Hello!

Maybe you can first import the data into a vector and then look for the maximum and minimum like this:

A=importdata('sl.txt');
B=A.data;
mx=max(B(:,2))
mn=min(B(:,2))

This code should work!

Pedro

[Prateek Srivastava]

But the idea is to find all the max and min peaks that is the points.

Answer 2

[Image Analyst]

To find the "valleys", simply invert the signal

[peakHeights, indexesOfPeaks] = findpeaks(stress);
[valleyHeights, indexesOfValleys] = findpeaks(-stress);  % Note the minus sign!
valleyHeights = abs(valleyHeights); % Correct for inverting it.

[Prateek Srivastava]

thanks a lot for your answer I now understand my mistake but after this when I am trying to write the rain flow script in order to reduce a spectrum of varying stress there is this error which is showing"Error using load Must be a string scalar or character vector.I am also attaching the script thanks in advance for your help.

[Image Analyst]

You say:

load(i+1:i+2)=[];

but load() is a function that takes a filename string. However you're using it as an array. The solution is simple: use a different name for your "load" variable so that it does not conflict with a built in function.

[Prateek Srivastava]

yeah I got your point that load is a function that takes file name string so what can I use to copy the ith element of the array "load" to the variable s1?

[Image Analyst]

Again, don't call it load. Call it thisLoad or something. Then to copy the ith element of that to s1, do this

s1 = thisLoad(i);