Re: Approx mode creates largedr matricies


Steen Schmidt wrote:
Scott Chapin wrote:

Not that it matters, I guess, but when I save matricies in
approximate mode, the files are 66% larger than when saved in exact
mode. I don't know that that is a linear relationship though.

Strange, but not really.

Not strange at all. The objects are different types, hence use
different amounts of memory.

An exact matrix (TYPE 29) uses memory (in bytes) following this formula:

5+rows*5+contents

A numeric array (TYPE 3) uses memory (in bytes) following this formula:

15+rows*columns*8

For the curious I can tell you that the TI89 only has one matrix type,
and that uses memory following this pattern:

4+rows*2+contents-rows*columns*2

The above means that matrices with integer contents are almost
identical in size on the two machines, while arrays with numeric
contents use considerably more space on the TI than on the HP. Symbolic
arrays generally use up considerably less space on the TI though, since
symbolic objects usually are stored using less memory on the TI.

Regards
Steen

Thanks Steen,

I figured there is more info in approximate mode, but what was strange
is that a recalled matrix (stored in exact mode) shows the radix, even
when recalled in exact mode. With these radicies (sp?) in the matrix,
BYTES still returns the smaller size.

Scott

.

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