How to use C=aLb formula to calculate cost?

Question

I'm calculating software development cost.

I don't know what do to with given formula so I need explanation.

  C=aLb

Where    
    C = Costs  
    L= size  (Line of code in thousand lines of code e.g 400)
    a and b are constants

Constants are as follows at link:

Constants

            E = 2.4 * (400)1.05 = 1295.31 PM
            D = 2.5 * (1295.31)0.38=38.07 PM  

How the value of E = 1295.31 is came?
Also how to use C=aLb formula?

Answer 1

I think the formula should be $C=aL^b$, not $C=aLb$. If you look at your first example, where $L=400$, $a=2.4$ and $b=1.05$, you have

$400^{1.05} = 539.7131$

$C = 2.4 \times (400)^{1.05} = 2.4 \times 539.7131 = 1295.3114$

which matches the value in the example.

To use the formula, take the number of lines of code, divide this by $1,000$ to get $L$, raise this to the power of the constant $b$ to get $L^b$, then multiply this by the constant $a$ to get $aL^b$.