"""
Ex 6.11 from A primer on ...
"""

#Dictionary representation of polynomial
#p = -3+2*x**3-x**5
p = {0: -3, 3: 2, 5: -1}

def eval_poly_dict(poly, x):
    sum = 0.0
    for power in poly:
        sum += poly[power]*x**power
    return sum

#Evaluate p for x = 1 and x = 2
print(f'p(x=1) = {eval_poly_dict(p,1)}, p(x=2) = {eval_poly_dict(p,2)}')

def diff(p):
    dp = {}
    for j in p:
        if j != 0:
            dp[j-1] = j*p[j]
    return dp

print(p)
print(diff(p))

"""
Terminal> poly_diff.py
p(x=1) = -2.0, p(x=2) = -19.0
{0: -3, 3: 2, 5: -1}
{2: 6, 4: -5}
"""