Infinity and one norm question

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SUMMARY

The discussion focuses on the differences between the one norm and infinity norm of a complex vector \( x \) and its conjugate transpose \( x^* \). It is established that while the 2-norm remains invariant under conjugation, the one and infinity norms do not share this property for complex vectors. The infinity norm of \( x^* \) is defined as \( \max |x_j^*| \) for \( 1 \leq j \leq n \). The norms are equal for real vectors, as demonstrated by the relationship \( |z^*| = |z| \) for complex numbers.

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Visceral
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Hi,

I was wondering why the one and infinity norm of a complex vector x are not equal to the the one and infinity norm of x* (the conjugate transpose of x)? This seems to be true for the 2-norm, but I am not sure why for these other norms.
 
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What is your definition of infinity norm of x*?
 
the infinity norm of x* = (x1*, x2*, ... , xn*)^T is

max|xj*| where 1≤j≤n

if that makes sense. Sorry, not good with latex on here. I think I might see now the infinity and one norm of a complex vector x may not be equal. However, they are equal if x is a real vector correct?
 
If z = x+iy is a complex number (x,y\in \mathbb R), then |z^*|= |x-iy| = x^2+ (-y^2)=x^2+y^2=|z|.
 

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