If D were the driving factor, it would be possible to express expected energy consumption E mathematically as:

`
E = k _{0} + k_{1}D^{n} ---(1)
`

and this could be represented graphically, although the characteristic line would be curved rather than straight. This is not a major problem, except that not many M&T software systems would have provision to accommodate such a case. A straight line is preferable in that respect. To force the graph to look like a straight line, one can manipulate D, and create a 'transformed' version of the driving factor, D', thus:

`
D' = D ^{n}
`

which transforms equation (1) into the familiar straight-line model:

`
E = k _{0} + k_{1}D'
`

It is not just simple clean curves which can be transormed in this fashion. Quite complex discontinuous functions could also be tamed in an analogous way.

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