def zero_crossing(trace, base=15, shift=10, chi=0.6, falling=True):
"""
NIMA 775 (2015) 71–76
"""
try:
bs = numpy.average(trace[0:base])
inv = numpy.zeros(trace.shape)
inv[shift:] = trace[0:-shift] - bs
zc = chi * (trace - bs) - inv
if falling:
zc *= -1
t_lim, = numpy.unravel_index(zc.argmax(), zc.shape)
t0 = numpy.argmax(zc[t_lim:] < 0) + t_lim
t_zc = numpy.arange(t0 - 3, t0 + 3)
y_zc = zc[t0 - 3:t0 + 3]
cs = CubicSpline(t_zc, y_zc)
r = cs.solve(0.0)
for ri in r:
if numpy.isreal(ri) and t_zc[0] < ri < t_zc[-1]:
return ri
except ValueError:
pass
return 0
def fluxFunc(x):
return -1 * cs(x, 1)
flux = fluxFunc(thermocline)
print("The flux at", thermocline.item(0), "m is ", flux.item(0))
plt.figure()
plt.plot(x, y, 'o', label='data')
plt.plot(xs, cs(xs), label="C (℃/m)")
plt.plot(xs, cs(xs, 1), label="C'")
plt.plot(xs, cs(xs, 2), label="C''")
plt.legend()
plt.figure()
plt.plot(xs, -1 * cs(xs, 1), label=r"J $ \left( \frac{cal}{m^2s}\right)$")
plt.legend()
#plt.plot(x, f(x), label="S'")
plt.show()
tempat17 = cs(1.7)
depthat50 = cs.solve(50)
print("Depth at 50 degrees is ", depthat50.item(0), "m")
print("Temperature at 1.7 m is ", tempat17.item(0))
