5.1.8 iparm(_JT_ norm_) - norm

• Current index: 8
• Intent: In
• Default: _JT_ norm_ 2_
• Values:

  Variable	Meaning	Value
  _JT_ norm_ inf_	| x|$\infty$ = $$\max_{1 \le i \le n}^{}$$| xi|  ,  | A|$\infty$ = $$\max_{1 \le i \le n}^{}$$$$\sum_{j=1}^{m}$$| aij|	0
  _JT_ norm_ 1_	| x|1 = $$\sum_{i=1}^{n}$$| xi|  ,  | A|1 = $$\max_{1 \le j \le m}^{}$$$$\sum_{i=1}^{n}$$| aij|	1
  _JT_ norm_ 2_	| x|2 = $$\sqrt{\sum_{i=1}^n x_i^2 }$$  ,  | A|F = $$\sqrt{\sum_{i=1}^n \sum_{j=1}^m a^2_{ij} }$$	2

  where x is a vector of length n and A is an n by m matrix.

• NOTES:
  • The 2-norm is the only norm currently implemented for all matrix storage formats.
  • Note that the matrix 1-norm is expensive to calculate for matrices stored in some formats (e.g.ELL storage).