fft.texi, cheb.texi

[Sean Harbour <sean at sychron dot com>]

Hi,

1. --

I noticed that the example in the file "doc/fft.texi" contains references to an
undefined variable "z", should this be "data" (first few lines).

i.e.

  for (i = 0; i < 128; i++)
    @{
       REAL(z,i) = 0.0;
       IMAG(z,i) = 0.0;
    @}

becomes...

  for (i = 0; i < 128; i++)
    @{
       REAL(data,i) = 0.0;
       IMAG(data,i) = 0.0;
    @}

2. --

Also, in the example in file "doc/cheb.texi"

  for (x = 0; x < 1; x += 0.001)
    @{
      double r10 = gsl_cheb_eval_n (cs, 10, x);
      double r40 = gsl_cheb_eval (cs, x);
      printf ("%g %g %g %g\n", x, GSL_FN_EVAL (&F, x), r10, r40);
    @}

The step size is a power of 10 and doesn't have an exact binary representation.
"0.00125" may be better (at least give it a fighting chance) or similar --
people will use this as reference code.

3. --

Again in "doc/cheb.texi" "order" is used where I would expect "degree" to be
used, and "term" where I would expect "order" to be used.
That is, the usual relationship between degree and order is that "order =
degree+1" (as in a polynomial of degree 2 has order 3, a quadratic).


Best wishes,

Sean.