etime

Elapsed time

Syntax

• e = etime(t2,t1)
  

Description

e = etime(t2,t1) returns the time in seconds between vectors t1 and t2. The two vectors must be six elements long, in the format returned by clock:

• T = [Year Month Day Hour Minute Second]
  

Examples

Calculate how long a 2048-point real FFT takes.

• x = rand(2048,1);
  t = clock; fft(x); etime(clock,t)
  ans =
        0.4167
  

Limitations

As currently implemented, the etime function fails across month and year boundaries. Since etime is an M-file, you can modify the code to work across these boundaries if needed.

etree

Elimination tree

Syntax

• p = etree(A)
  p = etree(A,'col')
  p = etree(A,'sym')
  [p,q] = etree(...)
  

Description

p = etree(A) returns an elimination tree for the square symmetric matrix whose upper triangle is that of A. p(j) is the parent of column j in the tree, or 0 if j is a root.

p = etree(A,'col') returns the elimination tree of A'*A.

p = etree(A,'sym') is the same as p = etree(A).

[p,q] = etree(...) also returns a postorder permutation q of the tree.

etreeplot

Plot elimination tree

Syntax

• etreeplot(A)
  etreeplot(A,nodeSpec,edgeSpec)
  

Description

etreeplot(A) plots the elimination tree of A (or A+A', if non-symmetric).

etreeplot(A,nodeSpec,edgeSpec) allows optional parameters nodeSpec and edgeSpec to set the node or edge color, marker, and linestyle. Use '' to omit one or both.