PsiMakeInput (freq,expr,[deduct,limit,]...)

PsiMakeInput() computes a generalized compounding of an arbitrary expression. Specifically, PsiMakeInput compounds the expr argument, freq number of times.  For example, for the function, PsiMakeInput(100, PsiNormal(0,1)); PsiNormal(0,1) will be compounded 100 times. 

Note that distribution compounding using PsiMakeInput() produces a more general case then distribution compounding using Analytic Solver’s PsiCompound(). (See the PsiCompound() entry in this chapter for more information on this function.)  For example, PsiNormal(0,1, PsiCompound(100)) is similar to PsiMakeInput(100, PsiNormal(0,1)).  Both compute the same trials, but only the former is a true distribution. The latter is considered an uncertain input, because the expr expression, in this case PsiNormal(0,1), could be more general then a single distribution.  For instance, take the example, =PsiMakeInput(100, PsiNormal(0,1) + 2 * B1 where B1 contains a new formula or distribution.  The entire expression, PsiNormal(0,1) + 2 * B1, will be compounded 100 times. 

Argument Descriptions:

Freq: Enter a number or expression for the frequency of compounding.  Enter 1 for no compounding.

Note: 

  1. If a fractional value is passed directly or indirectly (by using a formula) or a continuous distribution is passed to this argument, the result will be rounded down to the nearest integer.  
  2. If a discrete distribution is passed to this argument, the frequency distribution must be formulated in such a way that the trial values generated by the distribution must be greater than 1.  If not, trial values < 1 will be set equal to 1. 

Expr:  A Psi Distribution function or a cell containing a Psi Distribution function. 

Deduct: (Optional) Enter a number to be deduced during compounding. 

  • Note:  The value passed to the deduction argument is subtracted from every term of the compound sum which results in a shift of the compound distribution by -N * deduction.

Limit: (Optional) Enter a number as a limit during compounding. 

  • Note:  If a trial value is larger than a specified limit, then the trial value is reset to the limit.

This function was introduced to coincide with the release of the Convert @Risk feature which automatically converts @Risk functions to Psi functions.  (For more information on this new functionality, see Convert @Risk Functions within the “Using the Ribbon and Task Pane” chapter that appears at the beginning of this guide.)

The two functions RiskCompound and RiskMakeInput are converted into PsiMakeInput.  Note:  RiskMakeInput is a case of RiskCompound when freq = 1.