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Old 01-22-2019, 10:01 PM
Fromdusktilldawn Fromdusktilldawn is offline
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Default Assumption in Problem 3.9

In Problem 3.9, it stated that X^TX is positive definite

Which means it is also invertible

But on page 85, it said that X^TX might not be invertible.

Can someone explain this disparity?
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Old 01-23-2019, 02:02 AM
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htlin htlin is offline
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Default Re: Assumption in Problem 3.9

Problem 3.9 asks you to solve a special case (invertible case) of the more general task (on page 85).

Hope this helps.
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