I need to convert this code(excell) to matlab language help?

Function ZFactor(Tr, Pr)
    a = 0.064225133
    b = 0.53530771 * Tr - 0.61232032
    c = 0.31506237 * Tr - 1.0467099 - 0.57832729 / Tr ^ 2
    d = Tr
    e = 0.68157001 / Tr ^ 2
    f = 0.68446549
    g = 0.27 * Pr
    Newton-Raphson iteration (commented due to unstability and convergence problems
    rho = 0.27 * Pr / Tr  'Initial guess
    rhoold = rho
    For i = 1 To 100
        frho = a * rho ^ 6 + b * rho ^ 3 + c * rho ^ 2 + d * rho + e * rho ^ 3 * (1 + f * rho ^ 2) * Exp(-f * rho ^ 2) - g
        dfrho = 6 * a * rho ^ 5 + 3 * b * rho ^ 2 + 2 * c * rho + d + e * rho ^ 2 * (3 + f * rho ^ 2 * (3 - 2 * f * rho ^ 2)) * Exp(-f * rho ^ 2)
        rho = rho - frho / dfrho       test = Abs((rho - rhoold) / rho)
       If test < 0.00001 Then Exit For
        rhoold = rho
    Next i
    ZFactor = 0.27 * Pr / rho / Tr

Answer 1

[Image Analyst]

Function, For, If, Abs, and Exp go to function, if, for, abs, and exp (all lower case). Next i goes to end.

Put a % symbol in front of the "Newton-Raphson ...." line.

The function line should look like

Function output = ZFactor(Tr, Pr)

and the last line should be

output = 0.27 * Pr / rho / Tr

"To" in the for statement should be replaced with a colon :.

This

If test < 0.00001 Then Exit For

should be

if test < 0.00001 
    break;
end

Other than that I think it should be okay. You might want to add semicolons at the end of the lines to suppress echoing the result to the command window.

[Hakki]

thanks