X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Foutput%2Fcharts%2Fspreadlevel-plot.c;h=e4fed6178666fdfe4fbe9fc161d697fc50c17d65;hb=e91782a2d25dec932c93b7a57bd03d836614ba43;hp=44e2c658a93464c025ccc4a8bb34fa483935f31c;hpb=3dd0f6ae0d5eb73a2270a243e443c4ae03c2c16e;p=pspp

diff --git a/src/output/charts/spreadlevel-plot.c b/src/output/charts/spreadlevel-plot.c
index 44e2c658a9..e4fed61786 100644
--- a/src/output/charts/spreadlevel-plot.c
+++ b/src/output/charts/spreadlevel-plot.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2012 Free Software Foundation, Inc.
+   Copyright (C) 2012, 2020 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -53,10 +53,11 @@ spreadlevel_plot_add (struct chart_item *ci, double spread, double level)
 {
   struct spreadlevel_plot_chart *sl = to_spreadlevel_plot_chart (ci);
 
-  if ( sl->tx_pwr == 0)
+  /* Zero has a special meaning, in this implementation.  */
+  if (sl->tx_pwr == 0)
     {
-      spread = log (spread);
-      level = log (level);
+      spread = log (fabs (spread));
+      level = log (fabs (level));
     }
   else
     {