FCEXEC

The FCEXEC command executes a forecast based on the parameters options specified by the FCSET command for the forecast. The FCEXEC command implicitly loops over all the dimensions of the expression other than the time dimension.

You must use the FCEXEC command in combination with other OLAP DML statements as outlined in "Forecasting Programs".

Syntax

FCEXEC handle-expression [choice] time-series-expression

where choice is one or more of the following:

     TIME time-dimension
     TRADINGDAYS expression
     INTO name
     SEASONAL name
     SMSEASONAL name
     BACKCAST

Arguments

handle-expression: An INTEGER expression that specifies the handle to a forecasting context previously opened using the FCOPEN function.
TIME time-dimension: The name of the time dimension. You do not have to specify this parameter when one dimension of the time-series-expression is of type DAY, WEEK, MONTH, QUARTER, or YEAR.
TRADINGDAYS expression: An INTEGER expression that specifies the number of business days in the unit of time of the time data type (that is, DAY, WEEK, MONTH, or YEAR) of the time-series-expression. By default the value is the total number of days in the unit of time.
INTO name: The name of the Oracle OLAP variable in which the forecasting engine stores the forecast data. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when Oracle OLAP executes the forecast, it limits each of these additional dimensions to the first value in the dimension's status list.).

Important:
When you do not specify INTO and the time-series-expression names an Oracle OLAP variable, the forecasting engine populates the input variable with the output data of the forecast, thus overwriting the original data.
SEASONAL name: The name of the variable that the forecasting engine populates with the data that represents seasonal factors.The forecasting engine produces only one cycle of factors and stores these values into this variable beginning with the first time period in status. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when the forecasting engine executes the forecast, Oracle OLAP limits each of these additional dimensions to the first value in the dimension's status list.)
SMSEASONAL name: The name of the variable that the forecasting engine populates with the data that represents smoothed seasonal factors. The forecasting engine produces only one cycle of factors and stores these values into this variable beginning with the first time period in status; all other values are set to NA. This variable must be dimensioned by the time dimension and any other dimensions of the time-series-expression that have more than one value in status. (This variable can have additional dimensions. However, in this case, when the forecasting engine executes the forecast, Oracle OLAP limits each of these additional dimensions to the first value in the dimension's status list.)
BACKCAST: The BACKCAST keyword specifies that the forecasting engine returns fitted historical data. Typically this data is available only for a subset of the historical periods (sometimes called the "fit window"). The forecasting engine sets the value of the data that corresponds to the historical time periods that are outside of the fit window to NA.

Important:
When you specify a value for BACKCAST and do not specify a value for INTO variable, the forecasting engine populates the source variable with the backcasted data, thus overwriting the original data.
time-series-expression: An expression that specifies the data from which FCEXEC calculates values. The time-series-expression must be a numeric expression that is dimensioned by time-dimension. The time-series-expression may also be dimensioned by other dimensions. In this case, FCEXEC implicitly loops over all the dimensions of the expression other than the time dimension. The maximum status length of the time-series-expression is 5000.

Notes

Forecasting a Single Value

The FCEXEC command implicitly loops over all the dimensions of the time-series expression other than the time dimension. When you want to forecast only one value of a multidimensional time-series expression, then you must limit the status of all non-time dimensions to a single value before you execute the FCEXEC command.

Examples

Example 14-9 A Forecasting Program

Suppose you define a program named autofcst to perform a forecast from the data that is in an input variable named fcin1. The fcin1 variable is dimensioned by a time dimension named timedim. Assume that you have defined a program named autofcst with the following definition and specification.

DEFINE autofcst PROGRAM
PROGRAM
" Using the Automatic forecasting method 
" Suppose you want to create a forecast from the data in 
" an input variable named fcin1 that is dimensionsed by 
" a time dimension named timedim. 
"
" Open a forecasting context
hndl = FCOPEN('MyForecast')
" Initialize the target variables
fcout1 = NA
fcseas1 = NA
fcsmseas1 = NA
" Specify that the forecast be of the AUTOMATIC type
fcset hndl method 'automatic'
" Execute the forecast
FCEXEC hndl time timedim INTO fcout1 -
      seasonal fcseas1 smseasonal fcsmseas1 backcast fcin1
" Create a report showing the input and output of the forecast
REPORT DOWN timedim fcin1 fcout1 fcseas1 fcsmseas1
" Run a program named queryall to retrieve the characteristics 
" of the forecasting trials 
QUERYALL
" Close the forecasting context
FCCLOSE hndl
END

The autofcst program opens a forecasting context, sets the option of the forecast to AUTOMATIC, reports on the forecasted data, and queries and reports the characteristics of the various trials that Oracle OLAP performed to determine the method to use, and closes the forecasting context.

The autofcst program contains the following report command that displays a report of the input to and the output from the forecast.

REPORT DOWN timedim fcin1 fcout1 fcseas1 fcsmseas1

The sample report created by this statement follows.

TIMEDIM          FCIN1      FCOUT1    FCSEAS1   FCSMSEAS1
-------------- ---------- ---------- ---------- ----------
Jan97                  NA         NA 1.06725482 1.02926773
Feb97                  NA         NA .978607917 .945762221
Mar97                  NA         NA 1.12699278 .860505188
Apr97                  NA         NA .576219022 .905284834
May97                  NA         NA .920601317 .907019312
Jun97                  NA         NA 0.91118344  1.0580697
Jul97                  NA         NA 1.07886483 1.05597234
Aug97                  NA         NA 1.08101034   1.054612
Sep97                  NA         NA 1.08077427 1.05361672
Oct97               2,914         NA 1.08351799 1.05380407
Nov97               2,500         NA 1.01126778 1.04504316
Dec97               2,504         NA 1.08370549 1.03104272
Jan98               3,333         NA         NA         NA
Feb98               2,512         NA         NA         NA
Mar98               2,888         NA         NA         NA
...                 ...           ...        ...        ...
Jan01                  NA 3,371.7631         NA         NA
Feb01                  NA 2,736.4811         NA         NA
Mar01                  NA 3,408.3656         NA         NA
Apr01                  NA 714.277175         NA         NA
May01                  NA 2,502.9315         NA         NA
Jun01                  NA 3,195.3626         NA         NA
Jul01                  NA 3,911.6058         NA         NA
Aug01                  NA  4,000.651         NA         NA
Sep01                  NA 4,220.2658         NA         NA
Oct01                  NA 3,416.0208         NA         NA
Nov01                  NA 2,827.3943         NA         NA
Dec01                  NA 2,990.8629         NA         NA

The queryall program and a sample report created from its output is shown in "Querying a Forecast".