Functions > Data Analysis > Local Maximum and Minimum
Local Maximum and Minimum
The localmax and localmin functions are used to find local maxima and minima in 2D or 3D data sets.
For 2D data sets, the x data is recorded in the first column of matrix M1 and its associated response is in the second column.
For 3D data sets, the x and y data is recorded in the vector x and y respectively, and its associated response is in matrix M2.
localmax(M1, [w])—Returns a two-column matrix of the x and y values for each maximum found in the second column of matrix M1.
localmax(x, y, M2, [w])—Returns a three-column matrix of the x, y and z values for each maximum found in matrix M2.
localmin(M1, [w])—Returns a two-column matrix of the x and y values for each minimum found in the second column of matrix M1.
localmin(x, y, M2, [w])—Returns a three-column matrix of the x, y and z values for each minimum found in matrix M2.
When the optional window width w is greater than 1, each point in the data must be greater than the surrounding (2w + 1) points to be considered a local maximum to avoid false positives from noise.
Arguments
M1 is a real n x 2 matrix.
w (optional) is an integer ≥ 1, and its default value is 1.
x, y are real vectors.
M2 is a real matrix with the same number of rows as vector x, and the same number of columns as vector y has rows.