FUNCTION GROWTH

Growth

This function calculates predicted exponential growth by using existing data. GROWTH returns the y-values for a series of new x-values that you specify by using existing x-values and y-values. You can also use the GROWTH worksheet function to fit an exponential curve to existing x-values and y-values.

How does it work?

=GROWTH(known_y's,known_x's,new_x's,const)

where:


Known_y's is the set of y-values you already know in the relationship y = b*m^x.

- If the array known_y's is in a single column, then each column of known_x's is interpreted as a separate variable.

- If the array known_y's is in a single row, then each row of known_x's is interpreted as a separate variable.

- If any of the numbers in known_y's is 0 or negative, GROWTH returns the #NUM! error value.


Known_x's is an optional set of x-values that you may already know in the relationship y = b*m^x.

- The array known_x's can include one or more sets of variables. If only one variable is used, known_y's and known_x's can be ranges of any shape, as long as they have equal dimensions. If more than one variable is used, known_y's must be a vector (that is, a range with a height of one row or a width of one column).

- If known_x's is omitted, it is assumed to be the array {1,2,3,...} that is the same size as known_y's.


New_x's are new x-values for which you want GROWTH to return corresponding y-values.

- New_x's must include a column (or row) for each independent variable, just as known_x's does. So, if known_y's is in a single column, known_x's and new_x's must have the same number of columns. If known_y's is in a single row, known_x's and new_x's must have the same number of rows.

- If new_x's is omitted, it is assumed to be the same as known_x's.

- If both known_x's and new_x's are omitted, they are assumed to be the array {1,2,3,...} that is the same size as known_y's.


Const is a logical value specifying whether to force the constant b to equal 1.

- If const is TRUE or omitted, b is calculated normally.

- If const is FALSE, b is set equal to 1 and the m-values are adjusted so that y = m^x.


Remarks

- Formulas that return arrays must be entered as array formulas after selecting the correct number of cells.

- When entering an array constant for an argument such as known_x's, use commas to separate values in the same row and semicolons to separate rows.

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