Re: consistent crash using gammrnd

[David Bateman]

David Bateman wrote:
> Hermann wrote:
>   
>> Am Samstag, 14. Juli 2007 schrieb Paul Kienzle:
>>
>>   
>>     
>>>> gamrnd(rand(100,1),rand(100,1))
>>>>       
>>>>         
>>> The attached patch fixes the gamrnd bug ... it was doing
>>> vector/vector rather than vector./vector.
>>>     
>>>       
>> Hi,
>> I’m not sure, but maybe this should be .* instead of ./ ? I noted that 
>> in 'help randg' it sais
>>
>> | This can be used to generate many distributions:
>> |
>> | `gamma (a, b)' for `a > -1', `b > 0'
>> |            r = b * randg (a)
>>
>>   
>>     
> Well, yes and no.. The current definition of gampdf, gamcdf and gamrnd
> use a definition of 1/mu for the parameter B. So the current behavior of
> gamrnd is consistent with gamcdf, gampdf and gaminv. Unfortunately this
> seems to be the reverse of what is done in Matlab. For compatibility its
> probably better to mimic the matlab behavior. Consider the attached
> patch that changes the behavior to be consistent with matlab.. Note that
> exppdf, etc are also concerned are they are really just special cases of
> the gamma distributions.
>
> Do the other statistics functions have the same issues? I don't have the
> statistics toolbox for matlab and so can't easily check...
>
> D.
>   
Thinking about it further, there are the functions
deprecated/exponential_*  and deprecated/gamma_* that have effectively
had their behavior changed due to patch I just sent. To preserve
backward compatibility, the attached patch should also be applied.

D.

-- 
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 6 72 01 06 33 (Mob) 
91193 Gif-Sur-Yvette FRANCE                  +33 1 69 35 77 01 (Fax) 

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*** ./scripts/deprecated/gamma_rnd.m.orig44     2007-07-16 11:56:36.820032699 
+0200
--- ./scripts/deprecated/gamma_rnd.m    2007-07-16 11:57:25.810588673 +0200
***************
*** 34,39 ****
--- 34,43 ----
  
  function rnd = gamma_rnd (varargin)
  
+  if (nargin > 1)
+    varargin{2} = 1 ./ varargin{2};
+  endif
+ 
   rnd =  gamrnd (varargin{:});
  
  endfunction
*** ./scripts/deprecated/gamma_pdf.m.orig44     2007-07-16 11:56:43.277710702 
+0200
--- ./scripts/deprecated/gamma_pdf.m    2007-07-16 11:57:57.380012261 +0200
***************
*** 29,34 ****
--- 29,38 ----
  
  function pdf = gamma_pdf (varargin)
  
+  if (nargin > 2)
+    varargin{3} = 1 ./ varargin{3};
+  endif
+ 
   pdf =  gampdf (varargin{:});
  
  endfunction
*** ./scripts/deprecated/gamma_cdf.m.orig44     2007-07-16 11:56:47.807484806 
+0200
--- ./scripts/deprecated/gamma_cdf.m    2007-07-16 11:58:04.293666876 +0200
***************
*** 29,34 ****
--- 29,38 ----
  
  function cdf = gamma_cdf (varargin)
  
+  if (nargin > 2)
+    varargin{3} = 1 ./ varargin{3};
+  endif
+ 
   cdf =  gamcdf (varargin{:});
  
  endfunction
*** ./scripts/deprecated/gamma_inv.m.orig44     2007-07-16 11:56:53.744188712 
+0200
--- ./scripts/deprecated/gamma_inv.m    2007-07-16 11:58:11.558303899 +0200
***************
*** 29,34 ****
--- 29,38 ----
  
  function inv = gamma_inv (varargin)
  
+  if (nargin > 2)
+    varargin{3} = 1 ./ varargin{3};
+  endif
+ 
   inv =  gaminv (varargin{:});
  
  endfunction
*** ./scripts/deprecated/exponential_rnd.m.orig44       2007-07-16 
11:57:04.304661901 +0200
--- ./scripts/deprecated/exponential_rnd.m      2007-07-16 11:59:11.102326537 
+0200
***************
*** 34,39 ****
--- 34,43 ----
  
  function rnd = exponential_rnd (varargin)
  
+  if (nargin > 0)
+    varargin{1} = 1 ./ varargin{1};
+  endif
+ 
   rnd =  exprnd (varargin{:});
  
  endfunction
*** ./scripts/deprecated/exponential_pdf.m.orig44       2007-07-16 
11:57:10.513352119 +0200
--- ./scripts/deprecated/exponential_pdf.m      2007-07-16 11:58:38.090977685 
+0200
***************
*** 28,33 ****
--- 28,37 ----
  
  function pdf = exponential_pdf (varargin)
  
+  if (nargin > 1)
+    varargin{2} = 1 ./ varargin{2};
+  endif
+ 
   pdf =  exppdf (varargin{:});
  
  endfunction
*** ./scripts/deprecated/exponential_cdf.m.orig44       2007-07-16 
11:57:14.673144541 +0200
--- ./scripts/deprecated/exponential_cdf.m      2007-07-16 11:58:52.764243914 
+0200
***************
*** 31,36 ****
--- 31,40 ----
  
  function cdf = exponential_cdf (varargin)
  
+  if (nargin > 1)
+    varargin{2} = 1 ./ varargin{2};
+  endif
+ 
   cdf =  expcdf (varargin{:});
  
  endfunction
*** ./scripts/deprecated/exponential_inv.m.orig44       2007-07-16 
11:57:20.819837778 +0200
--- ./scripts/deprecated/exponential_inv.m      2007-07-16 11:58:31.193322535 
+0200
***************
*** 29,34 ****
--- 29,38 ----
  
  function inv = exponential_inv (varargin)
  
+  if (nargin > 1)
+    varargin{2} = 1 ./ varargin{2};
+  endif
+ 
   inv =  expinv (varargin{:});
  
  endfunction

2007-07-16  David Bateman  <address@hidden>

        * deprecated/gamma_cdf.m, deprecated/gamma_inv.m,
        deprecated/gamma_pdf.m, deprecated/gamma_rnd.m,  
        deprecated/exponential_cdf.m, deprecated/exponential_inv.m,
        deprecated/exponential_pdf.m, deprecated/exponential_rnd.m:
        Preserve backward compatibility.