Chebyshev evaluation pseudocode

cheb.py

# Chebyshev evaluation with interval rescaled to [0,1]
xp = 2*x - 1 # remap to [-1,1] that Cheb basis is easier in

# Constant and linear terms
result = coeffs[0] + xp*coeffs[1]

# Recurrence for remaining terms
cur, prev = xp, 1
t = xp * 2

for c in coeffs[2:]:
    # Compute next-higher basis function from two previus ones
    cur, prev = t * cur - prev , cur
    # Accumulate contribution
    result += c * cur
    
return result