gnuplot：如何總結一個任意列表

Question

對於gnuplot，我有一個很大的（隨機生成的）數字列表，我想在總和中用作索引。我該怎麼做？

這是我的意思。比方說，數字的列表是

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

我有一個函數

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我現在要繪製的函數，在區間(-pi,pi)這是f(x,n)作爲n運行通過數字總和在list。

Answer 1

如果你能控制你的列表的樣子，請嘗試以下操作：

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 

這是結果：