
Section 6: Functions continue99




Statistical Functions


Accumulations


Executing the
The Σ+ function automatically gives several
different sums and products of the values in the X and Yregisters at once.
In order to make these values accessible for sophisticated statistics problems,
they are automatically placed by the calculator into a block of six storage
registers that you define with the ΣREG
function.


When you execute ΣREG , the HP41C prompts you
for a register address with
ΣREG _ _
The address you specify defines the beginning of a block of six statistical
registers.


If you have not specified a block of statistical registers using the
ΣREG function, the statistical registers will
automatically be R11 through
R16. But if you change the location of the
statistical registers, that change remains in effect until you change it again,
even while the HP41C is off.


Before you begin any calculations using the Σ+
key, you should first clear the storage registers used in accumulations by
executing the CLΣ (clear statistical registers)
function.


When you key in a number and press the Σ+ key,
the calculator performs each of the following operations:



1.

The number in the Xregister is added to the contents of the first statistical
register (the first statistical register is presently defined as
R11).



2.

The square of the number in the Xregister is added to the contents of the
second statistical register (presently defined as
R12).



3.

The number in the Yregister of the stack is added to the contents of the
third statistical register (presently defined as
R13).

