From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001
From: Joseph Hunkeler <jhunkeler@gmail.com>
Date: Wed, 8 Jul 2015 20:46:52 -0400
Subject: Initial commit

---
 sys/gio/elogd.x | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 sys/gio/elogd.x

(limited to 'sys/gio/elogd.x')

diff --git a/sys/gio/elogd.x b/sys/gio/elogd.x
new file mode 100644
index 00000000..b910a80c
--- /dev/null
+++ b/sys/gio/elogd.x
@@ -0,0 +1,27 @@
+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# ELOGD -- Extended range log function.  Logarithmic scaling function for
+# negative or partially negative data.  The function is piecewise, continuous,
+# monotonic, reasonably smooth, and most importantly, is defined for all x.
+#
+#			     10.0 < X		y = log(x)
+#	       -10.0 <= X <= 10.0		y = x / 10.0
+#	   X < -10.0				y = -log(-x)
+#
+# Axes scaled with this function should have ticks labelled, e.g., 10**3,
+# 10**2, 10**1, 0, -10**1, -10**2, -10**3.  The corresponding ticks for
+# the normal log function would have values like 10**-2 rather than -10**2,
+# hence it is not difficult to distinguish between the two functions.
+
+double procedure elogd (x)
+
+double	x
+
+begin
+	if (x > 10.0D0)
+	    return (log10 (x))
+	else if (x >= -10.0D0)
+	    return (x / 10.0D0)
+	else
+	    return (-log10 (-x))
+end
-- 
cgit