from pylab import *
from numpy import ma

xmin= -2.5*pi
xmax=  2.5*pi
trimx = pi/2  # crop edges so lines starting outside the plot area will be shown
ymin= -2.5*pi
ymax=  2.5*pi
trimy = pi/2 
X,Y = meshgrid( arange(xmin,xmax, pi/10),arange(ymin,ymax,pi/6) )
Z = arcsin(X + Y*1j)
U = real(Z)
V = imag(Z)

figure()
M = abs(Z) # color by abs
#M = angle(Z) # color by angle
Q = quiver( X, Y, U, V, M, units='x', width=0.022, scale=1/0.15, pivot='mid') 
plot(X, Y, 'k,') # dots: 'k.' 'k,' ',' 's'
axis([xmin+trimx, xmax-trimx, ymin+trimy, ymax-trimy])
title("arcsin(z)")

plt.savefig("arcsin_z_vector_field_01_Pengo.svg")
plt.savefig("arcsin_z_vector_field_01_Pengo.png")

show()