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Diffstat (limited to 'ipl/procs/step.icn')
| -rw-r--r-- | ipl/procs/step.icn | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/ipl/procs/step.icn b/ipl/procs/step.icn new file mode 100644 index 0000000..a6d8838 --- /dev/null +++ b/ipl/procs/step.icn @@ -0,0 +1,56 @@ +############################################################################ +# +# File: step.icn +# +# Subject: Procedure to generate in real increments +# +# Author: Ralph E. Griswold +# +# Date: April 6, 1993 +# +############################################################################ +# +# This file is in the public domain. +# +############################################################################ +# +# step(r1, r2, r3) generates real values from r1 to r2 in increments of +# r3 (default 1.0). It is the real equivalent of i to j by k. +# If r2 is null, the sequence is infinite and is the real equivalent +# of seq(). +# +# Beware the usual problems of floating-point precision. +# +############################################################################ + +procedure step(r1, r2, r3) + + r1 := real(r1) | stop("*** invalid argument to step()") + \r2 := real(r2) | stop("*** invalid argument to step()") + /r3 := 1.0 + (r3 := real(r3)) ~= 0.0 | stop("*** invalid argument to step()") + r2 +:= 1E-6 # stab at avoiding underrun + + if \r2 then { # bounded sequence + if r3 > 0.0 then { + while r1 <= r2 do { + suspend r1 + r1 +:= r3 + } + } + else { + while r1 >= r2 do { + suspend r1 + r1 +:= r3 + } + } + } + + else { # bounded sequence + repeat { + suspend r1 + r1 +:= r3 + } + } + +end |