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example_tanh.py
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example_tanh.py
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from cvp_approx import (
Function,
generate_approx_remez_cvp, generate_approx_remez,
generate_approx_cvp, dirty_supnorm,
PolyIndexListConditionner, PolyDegreeConditionner,
)
import numpy as np
import matplotlib.pyplot as plt
import bigfloat
if __name__ == "__main__":
func = Function(lambda x: bigfloat.tanh(x))
interval_lo, interval_hi = 0.01, 0.125
interval = interval_lo, interval_hi
NUM_TEST_PTS = 10
POLY_DEGREE = 8
# remez method
poly_remez_1 = generate_approx_remez(func, interval, poly_conditionner=PolyDegreeConditionner(POLY_DEGREE), epsilon=1e-6)
poly_remez_3 = generate_approx_remez(func, interval, poly_conditionner=PolyDegreeConditionner(POLY_DEGREE), epsilon=1e-6, num_iter=3)
poly_remez_5 = generate_approx_remez(func, interval, poly_conditionner=PolyDegreeConditionner(POLY_DEGREE), epsilon=1e-6, num_iter=5)
print("max_diff for remez 1 is ", dirty_supnorm(poly_remez_1 - func, interval))
print("max_diff for remez 3 is ", dirty_supnorm(poly_remez_3 - func, interval))
print("max_diff for remez 5 is ", dirty_supnorm(poly_remez_5 - func, interval))
# generating coefficients of polynomial approximation
poly_cvp_1 = generate_approx_cvp(func, interval, NUM_POINT=200, precision=60, poly_conditionner=PolyIndexListConditionner(range(0, POLY_DEGREE+1, 2)))
poly_cvp_2 = generate_approx_cvp(func, interval, NUM_POINT=120, precision=60, poly_conditionner=PolyIndexListConditionner(range(0, POLY_DEGREE+1, 2)))
print("max_diff for poly_cvp_1 is", dirty_supnorm(poly_cvp_1 - func, interval))
print("max_diff for poly_cvp_2 is", dirty_supnorm(poly_cvp_2 - func, interval))
#poly_remez_cvp = generate_approx_remez_cvp(func, interval, poly_degree=POLY_DEGREE, epsilon=1e-6, num_iter=1)
#print("max_diff for poly_remez_cvp is", dirty_supnorm(poly_remez_cvp - func, interval))
# graphical representation
fig = plt.figure() # an empty figure with no axes
fig.suptitle('No axes on this figure') # Add a title so we know which it is
x = np.linspace(interval_lo, interval_hi, 100)
tanh_y = np.array([func(v) for v in x])
poly_cvp_1_y = np.array([poly_cvp_1(v) for v in x])
poly_cvp_2_y = np.array([poly_cvp_2(v) for v in x])
poly_remez_1_y = np.array([poly_remez_1(v) for v in x])
poly_remez_3_y = np.array([poly_remez_3(v) for v in x])
poly_remez_5_y = np.array([poly_remez_5(v) for v in x])
#poly_remez_cvp_y = np.array([poly_remez_cvp(v) for v in x])
#error_y = np.array([(poly_remez_cvp - func)(v) for v in x])
plt.plot(x, tanh_y, label='tanh')
plt.plot(x, poly_cvp_1_y, label='poly_cvp_1')
plt.plot(x, poly_cvp_2_y, label='poly_cvp_2')
plt.plot(x, poly_remez_1_y, label='poly_remez_1')
plt.plot(x, poly_remez_3_y, label='poly_remez_3')
plt.plot(x, poly_remez_5_y, label='poly_remez_5')
#plt.plot(x, poly_remez_cvp_y, label='poly_remez_cvp')
#plt.plot(x, error_y, label='error')
plt.title("Simple Plot")
plt.legend()
plt.show()