gnuplot：如何总结一个任意列表

Question

对于gnuplot，我有一个很大的（随机生成的）数字列表，我想在总和中用作索引。我该怎么做？

这是我的意思。比方说，数字的列表是

list = [81, 37, 53, 22, 72, 74, 44, 46, 96, 27] 

我有一个函数

​​

我现在要绘制的函数，在区间(-pi,pi)这是f(x,n)作为n运行通过数字总和在list。

Answer 1

如果你能控制你的列表的样子，请尝试以下操作：

num = 10 

# Let the numbers be in a space separated string. 
# We can access the individual numbers with the word(string, index) function. 
list = "81 37 53 22 72 74 44 46 96 27" 

f(x,n) = cos(n*x) 

set terminal pngcairo 
set output "sum_cos.png" 

set xrange [-pi:pi] 
set samples 1000 

# Build the plot command as a macro. 
plt_cmd = "" 
do for [n=1:num] { 
    plt_cmd = sprintf("%s + f(x,%s)", plt_cmd, word(list,n)) 
} 

# Check what we have done so far. 
print plt_cmd 

titlestring = "{/Symbol S} cos(n_i*x), i = 1 ...".num 

# Finally plot the sum by evaluating the macro. 
plot @plt_cmd title titlestring 

这是结果：