ANEW -log_demo

NEEDS -gaussj
NEEDS -gnuplot

DOC
(*
	import numpy as np
	import matplotlib.pyplot as plt

	plt.subplots_adjust(hspace=0.4)
	t = np.arange(0.01, 20.0, 0.01)

	# log y axis
	plt.subplot(221)
	plt.semilogy(t, np.exp(-t/5.0))
	plt.title('semilogy')
	plt.grid(True)

	# log x axis
	plt.subplot(222)
	plt.semilogx(t, np.sin(2*np.pi*t))
	plt.title('semilogx')
	plt.grid(True)

	# log x and y axis
	plt.subplot(223)
	plt.loglog(t, 20*np.exp(-t/10.0), basex=2)
	plt.grid(True)
	plt.title('loglog base 4 on x')

	# with errorbars: clip non-positive values
	ax = plt.subplot(224)
	ax.set_xscale("log", nonposx='clip')
	ax.set_yscale("log", nonposy='clip')

	x = 10.0**np.linspace(0.0, 2.0, 20)
	y = x**2.0
	plt.errorbar(x, y, xerr=0.1*x, yerr=5.0+0.75*y)
	ax.set_ylim(ymin=0.1)
	ax.set_title('Errorbars go negative')

	plt.show()
*)
ENDDOC

: func1 ( F: t -- r ) -5e F/ FEXP ;
: func2 ( F: t -- r ) PI*2 F* FSIN ;
: func3 ( F: t -- r ) -10e F/ FEXP 20e F* ;
: func4 ( F: t -- r ) PI*2 F* FCOS ;

: log_demo ( -- )
	#2000 DOUBLE LARRAY t{
	0 FIGURE CLF TRUE GRID
	t{ 0e 20e #2000 LINSPACE
	S" Types of logarithmic plots" TITLE
	2 2 SUBPLOT
	  [SEMILOGY  0e 20e S" blue" ['] func1 #2000 FPLOT  SEMILOGY]
	  [SEMILOGX  0e 20e S" blue" ['] func2 #2000 FPLOT  SEMILOGX]
	  [LOGLOG    0e 20e S" blue" ['] func3 #2000 FPLOT    LOGLOG]
	  [SEMILOGX  0e 20e S" blue" ['] func4 #2000 FPLOT  SEMILOGX]
	SPEND 
	t{ }free ;