How to generate all the possible values for a vector?

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Parikshit Pareek 2017-6-29

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评论： Walter Roberson 2017-6-29

采纳的回答： Walter Roberson

I want to generate all the values of [r1;r2] such that 300<=r1,r2<=300. How can I do this?

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Answer 1

Walter Roberson 2017-6-29

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You cannot generate that. There are 4574883165222469632 representable double precision values for 300 <= r1, and 18437736874454810624 representable double precision values for r2 <= 300. Forming each pair of possibilities would give you 84350492031744868214373536880150970368 combinations, each 16 bytes long. That is just short of 2^130 bytes of storage required. There is not that much memory in the universe.

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Parikshit Pareek 2017-6-29

Thanks a lot.

Walter Roberson 2017-6-29

The exact counts would be different if you restricted to integers, but the answer would be much that same, that you could not do it: your limitation 300<=r1 says that r1 is any representable value that is at least 300, and your limitation r2<=300 says that r2 is any representable value that is at most 300, including negatives.

Perhaps there are other constraints such as the total of the two is to remain fixed?

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