# Finding several local maximum values in a given range and corresponding indices

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If we have a dataset "y" which consists of a sum of 5 gaussian peaks as function of time t, there will be 5 local maximum values in the whole y values. Basically, I would like to obtain the y axis maximum values and their corresponding t axis values. For example peak 1, has a maximum value 5 and it corresponds to t value of 19.

One can individually find the maximum values by giving a range say

[a ,i]=max(y(1:20));% locating maxima in a given range of the first peak

value_1= t(i); % Corresponding value of time for index i1.

One can repeat this 5 times by specifying the ranges for all peaks. Is there a better way to achieve the same result as an output in a single vector, and the corresponding time for those maxima in another vector . Thanks.

### Accepted Answer

Star Strider
on 27 Sep 2019

Use the Signal Processing Toolbox findpeaks function, or the islocalmax (R2017b and later) function.

##### 8 Comments

Star Strider
on 28 Sep 2019

Thank you.

‘I hope Matlab includes peak area determination just like OriginPro where one can pan the area of interest and determine its area.’

I doubt that’s an option, or if it is, I’ve not heard of it.

Fitting Gaussians is not difficult. See: Area under each peak for an illustration, including findpeaks calls. You can probably use that code with a few tweaks to use your own data. (I will help as necesary, since it’s my code. That code uses trapz, however it would probably not be very difficult to tweak it to use integral to calculate the areas, once the parameters of the Gaussians are known.)

### More Answers (1)

Image Analyst
on 28 Sep 2019

##### 0 Comments

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