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plottah

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An Erlang/LFE gnuplot process server

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plottah examples fourier-approx.lfe
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examples/fourier-approx.lfe 

(defmodule fourier-approx

  (export all))



;;; Original example:

;;; * https://gnuplot.sourceforge.net/demo_5.2/bivariat.8.gnu

;;;

(defun opts ()

  '(#(title "Finite summation of 10, 100, 1000 fourier coefficients")

    #(key "fixed right bottom vertical Right noreverse enhanced autotitle nobox")

    #(style "increment default")

    #(samples "500, 500")

    #(style "data lines")

    #(title "")

    #(xrange "[ -10.0000 : 10.0000 ] noreverse writeback")

    #(x2range "[ * : * ] noreverse writeback")

    #(yrange "[ -0.400000 : 1.20000 ] noreverse writeback")

    #(y2range "[ * : * ] noreverse nowriteback")

    #(zrange "[ * : * ] noreverse nowriteback")

    #(cbrange "[ * : * ] noreverse nowriteback")

    #(rrange "[ * : * ] noreverse nowriteback")))



(defun funcs-and-vars ()

  '(#("int2(x,y,d)" "(x>y-d*.5) ? 0 : (int2(x+d,y,d) + (f(x)+4*f(x+d*.5)+f(x+d))*d/6.)")

    #("ack(m,n)" "(m == 0) ? n + 1 : (n == 0) ? ack(m-1,1) : ack(m-1,ack(m,n-1))")

    #("min(x,y)" "(x < y) ? x : y")

    #("max(x,y)" "(x > y) ? x : y")

    #("gcd(x,y)" "gcd1(rnd(max(x,y)),rnd(min(x,y)))")

    #("rnd(x)" "int(x+0.5)")

    #("gcd1(x,y)" "(y == 0) ? x : gcd1(y, x - x/y * y)")

    #("fourier(k, x)" "sin(3./2*k)/k * 2./3*cos(k*x)")

    #("sum10(x)" "1./2 + sum [k=1:10]   fourier(k, x)")

    #("sum100(x)" "1./2 + sum [k=1:100]  fourier(k, x)")

    #("sum1000(x)" "1./2 + sum [k=1:1000] fourier(k, x)")

    #("delta" "0.2")

    #("k" "1000")))



(defun plot-args ()

  "sum10(x)   title '1./2 + sum [k=1:10]   sin(3./2*k)/k * 2./3*cos(k*x)',     sum100(x)  title '1./2 + sum [k=1:100]  sin(3./2*k)/k * 2./3*cos(k*x)',     sum1000(x) title '1./2 + sum [k=1:1000] sin(3./2*k)/k * 2./3*cos(k*x)'")