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authorJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
committerJoseph Hunkeler <jhunkeler@gmail.com>2015-07-08 20:46:52 -0400
commitfa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 (patch)
treebdda434976bc09c864f2e4fa6f16ba1952b1e555 /sys/vops/lz/arczl.x
downloadiraf-linux-fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4.tar.gz
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+# ARCZ -- Vector reciprocal with checking for zero divisors. If the result
+# of a divide would be undefined a user supplied function is called to get the
+# output pixel value.
+#
+# NOTE: in the interests of simplicity a somewhat arbitrary tolerance is used
+# to check for an undefined divide, i.e., a divide by zero or a divide by a
+# number small enough to cause floating point overflow. A better way to do
+# this would be to provide a machine dependent version of this operator in
+# host$as which catches the hardware exception rather than using a comparison.
+
+procedure arczl (a, b, c, npix, errfcn)
+
+long a # numerator
+long b[ARB], c[ARB] # divisor, and output arrays
+int npix # number of pixels
+long errfcn() # user function, called on divide by zero
+
+int i
+long divisor
+extern errfcn()
+errchk errfcn
+
+begin
+ if (a == 0) {
+ call aclrl (c, npix)
+ return
+ }
+
+
+ do i = 1, npix {
+ divisor = b[i]
+ if (divisor == 0)
+ c[i] = errfcn (a)
+ else
+ c[i] = a / divisor
+ }
+end