Programmer Guide/Command Reference/EVAL/ipeak: Difference between revisions
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;Result: A scalar or a vector containing the indices of the located peaks. | ;Result: A scalar or a vector containing the indices of the located peaks. | ||
:A value ''y''[i] is a peak if: | :A value ''y''[i] is a peak if: | ||
:: | ::# the index is in the range ''i1'' <= ''i'' <= ''i2'' | ||
::* ''y''[i] is greater than the threshold ''ymin''/''ymin''[i] | ::* ''y''[i] is greater than the threshold ''ymin''/''ymin''[i] | ||
::* (''y''[i-1]+''y''[i+1])/2 < ''y''[i] | ::* (''y''[i-1]+''y''[i+1])/2 < ''y''[i] | ||
::* ''y''[i-k-1] <= ''y''[i-k] and ''y''[i+k+1] <= ''y''[i+k]; with: k=0.. | ::* ''y''[i-k-1] <= ''y''[i-k] and ''y''[i+k+1] <= ''y''[i+k]; with: k=0..nwidth-1 | ||
Revision as of 10:07, 11 April 2011
Search the function y for local peaks and return either a scalar or a vector with indices of the peak values. The result can, for example, be passed directly to qinterp() to compute the interpolated peak coordinates.
- Usage
ipeak(y {, npeaks, i1, i2, nwidth, ymin})- y
- data vector (the function).
- npeaks
- the maximum number of peaks to locate (default=1)
- i1, i2
- the index range to be searched (default=1,
ncol(y)-1) - nwidth
- the minimum width of a peak (+/-) (default=1)
- ymin
- the threshold; must be a scalar or a vector with the same length as y (default: no threshold)
- Result
- A scalar or a vector containing the indices of the located peaks.
- A value y[i] is a peak if:
- the index is in the range i1 <= i <= i2
- y[i] is greater than the threshold ymin/ymin[i]
- (y[i-1]+y[i+1])/2 < y[i]
- y[i-k-1] <= y[i-k] and y[i+k+1] <= y[i+k]; with: k=0..nwidth-1
