Function printOrego

Example

// TypeScript usage example
import {printOrego} from 'diff-grok';

printOrego();
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# Python reference calculation for comparison
import numpy as np
import pandas as pd
from scipy.integrate import solve_ivp

# -------------------------
# 0. Solver method
# -------------------------
METHOD = "Radau"  # stiff solver recommended

# -------------------------
# 1. Define OREGO ODE
# -------------------------
def orego(t, y):
   y1, y2, y3 = y
   dy1 = 77.27 * (y2 - y1 * y2 + y1 - 0.000008375 * y1**2)
   dy2 = ( -y2 - y1 * y2 + y3 ) / 77.27
   dy3 = 0.161 * (y1 - y3)
   return [dy1, dy2, dy3]

# -------------------------
# 2. Initial conditions and time
# -------------------------
y0 = [1, 2, 3]
t_start = 0.0
t_end = 360.0
t_step = 0.01

# Use linspace to ensure t_eval within t_span
n_points = int(np.ceil((t_end - t_start) / t_step)) + 1
t_eval = np.linspace(t_start, t_end, n_points)

# -------------------------
# 3. Solve ODE
# -------------------------
sol = solve_ivp(
   orego,
   (t_start, t_end),
   y0,
   method=METHOD,
   t_eval=t_eval,
   rtol=1e-8,
   atol=1e-8
)

print("Success:", sol.success)
print("Message:", sol.message)

# -------------------------
# 4. Save solution to CSV
# -------------------------
data = np.column_stack((sol.t, sol.y.T))
col_names = ['t', 'y1', 'y2', 'y3']

df = pd.DataFrame(data, columns=col_names)
filename = f"OREGO-using-{METHOD}.csv"
df.to_csv(filename, index=False)

print(f"Solution saved to '{filename}'")
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