From 40e5a5811c6ffce9b0974e93cdd927cbcf60c157 Mon Sep 17 00:00:00 2001
From: Joe Hunkeler <jhunkeler@gmail.com>
Date: Tue, 11 Aug 2015 16:51:37 -0400
Subject: Repatch (from linux) of OSX IRAF

---
 pkg/xtools/doc/extrema.hlp | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 pkg/xtools/doc/extrema.hlp

(limited to 'pkg/xtools/doc/extrema.hlp')

diff --git a/pkg/xtools/doc/extrema.hlp b/pkg/xtools/doc/extrema.hlp
new file mode 100644
index 00000000..cea82502
--- /dev/null
+++ b/pkg/xtools/doc/extrema.hlp
@@ -0,0 +1,27 @@
+.help extrema Dec83 xtools
+.ih
+NAME
+extrema -- find the extrema in an array of x and y points
+.ih
+SYNOPSIS
+.nf
+nextrema = extrema (x, y, curvature, npts, dx)
+
+real	x[npts], y[npts]	# Input data points and output extrema
+real	curvature[npts]		# 2nd deriv. of cubic spline at extrema
+int	npts			# Number of input data points
+real	dx			# Precision of extrema positions
+.fi
+.ih
+DESCRIPTION
+The input data points are fitted with a cubic interpolation spline.  The
+spline is then searched for points where the first derivative changes sign.
+The minimum step size of this search is controlled by the parameter dx.
+The positions of these extrema are returned in the x array, the value of the
+spline at the extrema are returned in the y array, and the curvature or
+second derivative of the spline at the extrema are returned in the
+curvature array.  The function returns the number of extrema found.
+.ih
+SEE ALSO
+xtools.peaks
+.endhelp
-- 
cgit 

