Untitled

import numpy as np
import pandas as pd

# Given data points for vapor temperature and pressure

data = {
    "Temperature (°C)": [10.4, 20.3, 30.2, 39.5, 49.5, 60.9, 68.7, 78, 83, 90.3],
    "Pressure (Pa)": [19, 29, 37, 71, 112, 155, 265, 369, 522, 753],
}

# Convert data to DataFrame
df = pd.DataFrame(data)

# Extract temperature and pressure
x = np.array(df["Temperature (°C)"])
y_actual = np.array(df["Pressure (Pa)"])

# Trendline equations
# Linear: y = 7.95x - 189

y_linear = 7.95 * x - 189

# Polynomial: y = 146 - 9.92x + 0.175x^2
y_poly = 146 - 9.92 * x + 0.175 * x ** 2

# Cubic: y = -70.7 + 10.3x - 0.298x^2 + 3.13e-3 * x^3
y_cubic = -70.7 + 10.3 * x - 0.298 * x ** 2 + 3.13e-3 * x ** 3


# Function to calculate RMSE
def calculate_rmse(actual, predicted):
    return np.sqrt(np.mean((actual - predicted) ** 2))


# Calculate RMSE for each trendline

rmse_linear = calculate_rmse(y_actual, y_linear)
rmse_poly = calculate_rmse(y_actual, y_poly)
rmse_cubic = calculate_rmse(y_actual, y_cubic)

print(rmse_linear, rmse_poly, rmse_cubic)