Scalar from Two Matrix?

If a 3x3 matrix is S=[30 0 10; 0 30 10; 10 10 30] , and you know P=30.

The formula: W^2 = IISII^2 - P^2.

P is a scalar, and to count this formula you need S also to be scalar.

I have multiple S.*S or S.^2, and I still got 3x3 matrix. And that was pretty expected.

Anyhow, my point is, how can I get a scalar from IISII^2? Is that even possible?

Love

Regina

[Walter Roberson]

What does IISII mean in this context? Is it ||S|| ? Is that perhaps the determinant of S ?

[Richard Brown]

I think it's a norm. Try squaring norm(S). And if you don't know what that means, or which norm to use, you have bigger problems...

[Regina]

I think IISII is a scalar product or dot product, because IISII^2 = S.*S.

But in this case S is 3x3 matrix, and can't see this should be scalar.

But I don't know, hope you can help me guys.

By the way, is it a different between scalar product and scalar or are they just the same?

Answer 1

[bym]

|S||| denotes matrix norm, see

doc norm

[Regina]

okay, so, you can't get a scalar from ||S||, right?

[bym]

if ||S|| means norm, then it _is_ a scalar. As I said, look at the documentation for norm.