gnuplot：使用*圆*绘制参数函数（而不是使用点）

Question

以下gnuplot脚本有效：

set parametric  
set trange [0:5]  
set xrange [0:4]  
set yrange [0:6]  
plot t+log(t+1),t*t+sin(t) title 'Parametric example' with points

......但这并不是：

set parametric  
set trange [0:5]  
set xrange [0:4]  
set yrange [0:6]  
plot t+log(t+1),t*t+sin(t) title 'Parametric example' with circles

用圆圈（而不是点）绘制的正确语法是什么，以及如何设置圆直径？

谢谢。

[编辑]

我尝试了以下但没有成功：

C:\gnuplot.exe  

    G N U P L O T  
    Version 4.6 patchlevel 0    last modified 2012-03-04  
    Build System: MS-Windows 32 bit  

    Copyright (C) 1986-1993, 1998, 2004, 2007-2012  
    Thomas Williams, Colin Kelley and many others  

    gnuplot home:     http://www.gnuplot.info  
    faq, bugs, etc:   type "help FAQ"  
    immediate help:   type "help"  (plot window: hit 'h')  

gnuplot changed the codepage of this console from 437 to 1252 to  
match the graph window. Some characters might only display correctly  
if you change the font to a non-raster type.  

Terminal type set to 'windows'  

gnuplot> set samples 11  

gnuplot> plot sample [t=0:2] '+' using (t+log(t+1)) : (sqrt(t)+sin(t)) : (0.05) with circles  
     undefined variable: sample  

gnuplot> plot samples [t=0:2] '+' using (t+log(t+1)) : (sqrt(t)+sin(t)) : (0.05) with circles  
     undefined variable: samples  

gnuplot> plot [t=0:2] '+' using (t+log(t+1)) : (sqrt(t)+sin(t)) : (0.05) with circles
     Pseudodata not yet implemented for polar or parametric graphs

gnuplot>

[EDIT2] 如果我调整图形的纵横比使得X和Y轴在屏幕上的比例相同，则圆圈不是圆形的。我花了很多时间搜索，但找不到合适的语法来解决这个问题。

Answer 1

sample关键字仅在gnuplot 5中引入。使用该版本，您的第一次尝试正常工作：

set samples 11
plot sample [t=0:2] '+' using (t+log(t+1)) : (sqrt(t)+sin(t)) : (0.05) with circles