gnuplot: smooth line in polar coordinates

I tried to plot some data in polar coordinates with gnuplot and then draw a smooth line.

data.dat:

0 10
20 15
40 40
60  80
80  140
100 140
120 80
140 40
160 15
180 10

gnuplot:

set polar
set angle degrees
set grid
set grid polar
plot "data.dat" smooth csplines

I expected gnuplot to draw ovoid curve between points, but it drew strange 开发者_JAVA百科line from left to right ignoring polar coordinates. Do you think there is any solution?

---

csplines are cubic so that's the best you can get with them. Try

plot 'data.dat' smooth bezier

but even then, you can't achieve much with such a small data set.

There is another trick you can try but it improves things only a little: you first output a table of the data generated by smooth bezier normal plot and then plot them polar:

# save smooth bezier data
set table
set output 'b_data.dat'
plot 'data.dat' smooth bezier

# plot
unset table
set term x11
set polar
set angle degrees
set grid
set grid polar
plot "b_data.dat" w lines