This family is about spreading a Total amount over time. It differs from other kinds of projections families because the function decides what the rate or level is required (based on distributions or formulae) to disburse the Total between the Start and Finish dates.

The Time Spread family is for spreading amounts over a time interval, and it is useful for budgeting and business planning, particularly for capital projects. The functions it contains offer different ways of spreading an amount over time:

• UniSpread does a simple uniform (flat) spread between a Start and a Finish date. This is a basic workhorse for lots of budgeting situations.
  
• SCurve spreads an amount according to what is know in costing circles as an 'S curve' . An S curve is simply a distribution that concentrates the amount in the centre of the time interval, and many kinds of distribution (normal, etc) will do this. We have preferred to use our own design of S curve, based on the integral of sin(time*skewness)+peakness which works out to be -cos(time*skewness) + peakness*time. This formula enables you to control the skewness and degree of peaking (centre concentration) of the curve. A companion function to SCurve, SCurveGrow, grows the amount prior to spreading it using an S-curve.
  
• Other ways of spreading an amount over time according to a statistical distribution are offered by DistSpread. With this function you specify the Start time, MidPoint, and Finish time, and you can then spread the Total using any of the distribution types available from the variable DistType, including the Uniform, Triangular, Double Triangular, Normal and Log Normal distributions.
  
• Two other functions, FStepSpread and TStepSpread, are hybrids between Time Spread functions and Stepped Rate Projections functions. They spread a Total amount according to sets of AnnualRates and either FromDates and ToDates. To get the correct Total amount disbursed, they calculate the Finish date (in the case of FStepSpread), or Start date (in the case of TStepSpread. These functions are useful in budgeting situations where you want to stipulate a specific rate of disbursement, but have an absolute amount you want disbursed which, once depleted, must not be exceeded.