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Content Type: text/plain
We have to begin somewhere, hopefully above the obvious and
somewhat below the uninteresting.
The MESA User Guide Supplement for Version 2.2 boasts 99,999 rows
per layer; 18,278 columns per layer; and 702 layers per worksheet.
Both columns and layers use alphabetic ranges for values, columns
from A...ZZZ and layers from A...ZZ.
More specifically there are three distinct alphabetic ranges
(A...Z, AA...ZZ, and AAA...ZZZ). The count in the first range is
26;the second, 676;and the third, 17,576. Thus in a new
spreadsheet beginning in column A we can enter the value of 26
(the count of A...Z) in row 1. In row 2 we can enter the formula
=A1^2 (the count of AA...ZZ). And in row 3, =A1^3 (the count of
AAA...ZZZ). If we do, the values of 26 (row 1), 676 (row 2), and
17,576 (row 3) appear respectively
Then in column A, row 4 we can enter the formula =SUM(A1:A2) and
in row 5, =SUM(A1:A3). This will give us our 702 (number of
layers) and 18,278 (number of columns). So we may not know how
the MESA authors came up with 99,999 as the upper limit on rows
per layer, but we have some confidence about their columns and
layers numbers.
In this exercise (in stupidity) only one cell, A1 contains a
value. The remainder contain formulas. If there is nothing
entered in A1, a default value of '0' is assumed in the formulas.
However, once we enter a value in A1 (through either pressing the
'Enter' key, an arrow key, or the 'Tab' key), the other calculated
values appear in their corresponding cells.
We have used only two of the builtin MESA functions, the
exponentiation ('^') operator and the SUM function. In the SUM
function we used cell ranges, A1:A3 (columns) and A1:A2 (layers).
Alternatively in cell A4 we could have written =SUM(A1+A1^2) for
the layers and in A5, =SUM(A4+A1^3). Notice that we could have
also written A5 as =SUM(SUM(A1+A1^2)+A1^3) or as
=SUM(SUM(A1:A2)+A3).
Thus we have different means of achieving the same results as in
regular programming. The principal difference between the two
lies in the "ambiguity" of a cell, whose "contents" may differ
from its "value". In this instance a cell's contents may be a
formula, but its value is the result of calculating the formula.
In regular programming, e.g. C, a cell, i.e. a variable name,
either represents data (a value) or a function (a formula or
algorithm).
For many, if not most, on this list we have not crossed into
uncharted territory. Nothing presented here lies outside your
experience. I offer this as a starting point from which we can
come to an understanding of what you want to know about equations
or formulas. This, I think, covers all the basics.
Let me know what you think as well as what further issues you
would like addressed.
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2001 ]
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