Re: A bug in spline

[Nicholas Jankowski]

On Thu, Jan 28, 2016 at 3:32 PM, 陳慶全 <address@hidden> wrote:

Hi, 

There is a bug in spline. 

I don't know where to report this, so I use this mail to send a bug.

For the complete case in function `spline`, when n > 2,

(line 138 ~ 139 in source code)

```

      g(2:n-1,:) = (a(3:n,:) - a(2:n-1,:)) ./ h(2:n-1) - ...

                   (a(2:n-1,:) - a(1:n-2,:)) ./ h(1:n-2);

```

should be

```

      g(2:n-1,:) = (a(3:n,:) - a(2:n-1,:)) ./ h(2:n-1, idx) - ...

                   (a(2:n-1,:) - a(1:n-2,:)) ./ h(1:n-2, idx);

```

and (line 147~150 in source code)

```

      d = d(1:n-1,:);

      c = c(1:n-1,:);

      b = b(1:n-1,:);

      a = a(1:n-1,:);

```

should be

```

      d = d(1:n-1,:); d = reshape(permute(d, [2, 1]), 1, []);

      c = c(1:n-1,:); c = reshape(permute(c, [2, 1]), 1, []);

      b = b(1:n-1,:); b = reshape(permute(b, [2, 1]), 1, []);

      a = a(1:n-1,:); a = reshape(permute(a, [2, 1]), 1, []);

```

sincerely,

ChingChuan Chen 

Thanks!  You could create a bug report over at

http://bugs.octave.org/

Then the people familiar with the sourcecode and this function could check the changes, make sure things still work as expected, and put a patch together if confirmed. This would keep your report from getting lost in the email-shuffle.

Thanks!

nick j.