RE: Fwd: qfunc/qfuncinv implementation in communications package

[Richardson, Anthony]

Przemek Klosowski wrote:
> On 01/24/2013 04:33 PM, Richardson, Anthony wrote:
> 
> >
> > Octave 3.6.3 returns zero for both forms:
> > [x=[0:3:18]' qfunc(x) erfc(x/sqrt(2))/2]
> >
> >       0.000000000000000    0.500000000000000    0.500000000000000
> >       3.000000000000000    0.001349898031630    0.001349898031630
> >       6.000000000000000    0.000000000986588    0.000000000986588
> >       9.000000000000000    0.000000000000000    0.000000000000000
> >      12.000000000000000    0.000000000000000    0.000000000000000
> >      15.000000000000000    0.000000000000000    0.000000000000000
> >      18.000000000000000    0.000000000000000    0.000000000000000
> >
> > _______________________________________________
> > Are you using the default display "format"  (scientific notation)?
> 
> No, I did 'format long' to show full precision.

Try it with one of the exponential formats.  With 'format short  e'.   I get:

octave:24> [x=[0:3:18]' qfunc(x) erfc(x/sqrt(2))/2]
ans =

  0.0000e+000  5.0000e-001  5.0000e-001
  3.0000e+000  1.3499e-003  1.3499e-003
  6.0000e+000  9.8659e-010  9.8659e-010
  9.0000e+000  0.0000e+000  1.1286e-019
  1.2000e+001  0.0000e+000  1.7765e-033
  1.5000e+001  0.0000e+000  3.6710e-051
  1.8000e+001  0.0000e+000  9.7409e-073

'format long' is a fixed point 15 digit format. 

Tony