X-Received: by 2002:a6b:2746:: with SMTP id n67-v6mr7047639ion.90.1529426479332; Tue, 19 Jun 2018 09:41:19 -0700 (PDT)
X-Received: by 2002:aca:a883:: with SMTP id r125-v6mr719699oie.7.1529426479068; Tue, 19 Jun 2018 09:41:19 -0700 (PDT)
Path: csiph.com!xmission!weretis.net!feeder6.news.weretis.net!feeder.usenetexpress.com!feeder-in1.iad1.usenetexpress.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!u78-v6no208830itb.0!news-out.google.com!c20-v6ni104itc.0!nntp.google.com!u78-v6no208826itb.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
Newsgroups: comp.graphics.apps.gnuplot
Date: Tue, 19 Jun 2018 09:41:18 -0700 (PDT)
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=95.91.210.128; posting-account=dOCFDgoAAADjxX1_Z07BOmxhzKhUF2Q5
NNTP-Posting-Host: 95.91.210.128
User-Agent: G2/1.0
MIME-Version: 1.0
Message-ID: <a7122b88-09e6-4e90-a094-09d175c8b66b@googlegroups.com>
Subject: consistency of function .vs. data plotting
From: palme@kapott.org
Injection-Date: Tue, 19 Jun 2018 16:41:19 +0000
Content-Type: text/plain; charset="UTF-8"
Lines: 27
Xref: csiph.com comp.graphics.apps.gnuplot:3972

Hi all,

I am quite new to gnuplot, so maybe I am just not knowing some basics.

My understanding of the documentation is that something like "plot f(x)" is equivalent to "plot '+' using 1:(f($1))". 

Of course the former uses "set style function" as default plotting style, and the latter "set style data", but that's not my point...

My issue is that if f(x)=asin(x) the result is different: plotting the pure function does NOT plot points for the complex results in the range outside [-1,1]. 

But the approach using the pseudo data file plots also points for the complex results outside the [-1,1] range.

See yourself:
  print "using pure function"
  plot asin(x)
  pause -1 "press enter"
  print "using pseudo data file"
  plot '+' using 1:(asin($1)) with lines
  pause -1 "press enter"

So I have two questions:

1) Where exactly is my misunderstanding of the documentation, regarding the way how data file plotting works in comparison to plotting pure functions?

2) How can I avoid these complex results to be plotted with the second approach?

Thanks and regards
-stefan-