Fixed using SPlot with a function wroted by string

examples/3d_surface_plot.rb

@@ -0,0 +1,13 @@
+require "gnuplot"
+
+Gnuplot.open do |gp|
+ Gnuplot::SPlot.new( gp ) do |plot|
+ plot.grid
+
+ plot.data = [
+ Gnuplot::DataSet.new( "x**2+y**2" ) do |ds|
+	ds.with = "pm3d"
+ end
+ ]
+ end
+end

lib/gnuplot.rb

@@ -91,8 +91,12 @@ def initialize (io = nil, cmd = "plot")
  @arbitrary_lines = []
  @data = []
  yield self if block_given?
- puts "writing this to gnuplot:\n" + to_gplot + "\n" if $VERBOSE 
- io << to_gplot if io
+ puts "writing this to gnuplot:\n" + to_gplot + "\n" if $VERBOSE
+
+ if io 
+ io << to_gplot
+ io << store_datasets
+ end
  end
  attr_accessor :arbitrary_lines
 
@@ -137,14 +141,18 @@ def to_gplot (io = "")
  @sets.each { |var, val| io << "set #{var} #{val}\n" }
  @arbitrary_lines.each{|line| io << line << "\n" }
 
- if @data.size > 0 then
+ io
+ end
+
+ def store_datasets (io = "")
+ if @data.size > 0
  io << @cmd << " " << @data.collect { |e| e.plot_args }.join(", ")
  io << "\n"
 
  v = @data.collect { |ds| ds.to_gplot }
 	io << v.compact.join("e\n")
  end
-
+ 
  io
  end
  end
@@ -158,16 +166,6 @@ def initialize (io = nil, cmd = "splot")
  def to_gplot (io = "")
  @sets.each { |var, val| io << "set #{var} #{val}\n" }
 
- if @data.size > 0 then
- io << @cmd << " " 
- io << @data.collect { |e| e.plot_args }.join(", ")
- io << "\n"
-
- @data.each do |ds| 
- io << ds.to_gsplot << "e\n"
- end
- end
-
  io
  end