CODEWITHSUNDEEP
pythonpython-3.x
Ian Jones
Ian Jones

Reputation: 61

What is a more elegant, correct way to perform this loop?

My water density calculation has a 4th order polynomial equation in it. I use a loop to solve the polynomial. I get the correct solution with a while loop; unfortunately, I don't understand for-in loop syntax well enough to make that work instead:

# Density of water in kg/m^3 wrt temperature (degC) at 1 atmosphere

def densityWater(tDegC):
    #set up the counter, m
    m = 0

    #set up the data file (linear polynomial equation coefficients)
    #polynomial is of the form ex^4 + dx^3 + cx^2 + bx + a (x = tDegC)
    coeffWaterDensity = (-1.258606246688818E-07, 4.038794321262406E-05, -7.424005247974371E-03, 4.881970120567554E-02, 9.998909544205623E+02)

    densityH2O = 0

    while m < len(coeffWaterDensity):
        densityH2O = densityH2O + coeffWaterDensity[m] * tDegC ** (4 - m)
        m = m + 1
    return densityH2O

tDegC = input("At what temperature is the water you need the density for? Reply in celsius: ") tDegC = float(tDegC)

print("The density of water at "+ str(tDegC) + " celsius is " + "{:,.1f}".format(densityWater(tDegC)) + " kg/m^3")

But when I tried this for-in instead of the while loop, the result was incorrect

for m in range(len(coeffWaterDensity)):
    densityH2O = densityH2O + coeffWaterDensity[m] * tDegC ** (4 - m)
    m = m + 1
    return densityH2O

What is the most efficient and correct way to handle this?

Upvotes: 0

Views: 45

Answers (1)

aiven
aiven

Reputation: 4323

You return result of function inside loop. And don't need to increment m because for m in range(...) do it for you.

for m in range(len(coeffWaterDensity)):
    densityH2O = densityH2O + coeffWaterDensity[m] * tDegC ** (4 - m)
return densityH2O

Upvotes: 2

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