hyperu bug

[Paul van Wamelen <wamelen@marais.math.lsu.edu>]

Dear Pari developers,

Here is a patch for the hyperu bad input bug. The present implementation can
only deal with positive (real) third argument. (The function hyperu computes 
is actually defined for all complex z) 

Sincerely,
Paul van Wamelen.



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Index: TODO
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RCS file: /home/megrez/cvsroot/pari/TODO,v
retrieving revision 1.17
diff -c -r1.17 TODO
*** TODO	2000/02/21 18:22:34	1.17
--- TODO	2000/02/24 23:08:19
***************
*** 18,30 ****
  Unless specified otherwise, examples assume default precisions (on a 32
  bit machine)
  
- 5  "bad input" problems with hyperu:
-    ? hyperu(0,0,-1) \\ infinite loop
-    ? hyperu(1,2,0)
-    %1 = 51580834970224178120796801.23
-    ? hyperu(1,2,.0)
-    %2 = 2396734.892578125000000000000
- 
  5  setrand(5);thueinit(polsubcyclo(precprime(2^17),3))
    ***   non positive argument in mplog. \\ precision problem
  
--- 18,23 ----
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Index: doc/usersch3.tex
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RCS file: /home/megrez/cvsroot/pari/doc/usersch3.tex,v
retrieving revision 1.45
diff -c -r1.45 usersch3.tex
*** doc/usersch3.tex	2000/02/16 19:50:05	1.45
--- doc/usersch3.tex	2000/02/24 23:08:26
***************
*** 1023,1029 ****
  \syn{ggamma}{x,\var{prec}}.
  
  \subsecidx{hyperu}$(a,b,x)$: $U$-confluent hypergeometric function with
! parameters $a$ and $b$.
  
  \syn{hyperu}{a,b,x,\var{prec}}.
  
--- 1023,1030 ----
  \syn{ggamma}{x,\var{prec}}.
  
  \subsecidx{hyperu}$(a,b,x)$: $U$-confluent hypergeometric function with
! parameters $a$ and $b$. The parameters $a$ and $b$ can be complex but 
! the present implementation requires $x$ to be positive.
  
  \syn{hyperu}{a,b,x,\var{prec}}.
  
***************
*** 5587,5593 ****
  matrix whose diagonal entries are the coefficients of the squares, and the
  non-diagonal entries represent the bilinear forms. More precisely, if
  $(a_{ij})$ denotes the output, one has
! $$ q(x) = \sum_i a_{ii} (x_i + \sum_j>i a_{ij} x_j)^2 $$
  
  \syn{sqred}{x}.
  
--- 5588,5594 ----
  matrix whose diagonal entries are the coefficients of the squares, and the
  non-diagonal entries represent the bilinear forms. More precisely, if
  $(a_{ij})$ denotes the output, one has
! $$ q(x) = \sum_i a_{ii} (x_i + \sum_{j>i} a_{ij} x_j)^2 $$
  
  \syn{sqred}{x}.
  
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Index: src/basemath/trans3.c
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RCS file: /home/megrez/cvsroot/pari/src/basemath/trans3.c,v
retrieving revision 1.9
diff -c -r1.9 trans3.c
*** src/basemath/trans3.c	2000/02/17 18:44:47	1.9
--- src/basemath/trans3.c	2000/02/24 23:08:27
***************
*** 115,126 ****
  /**                                                                   **/
  /***********************************************************************/
  
! /* Assume gx > 0 and a,b real */
  GEN
  hyperu(GEN a, GEN b, GEN gx, long prec)
  {
    GEN x,y,p1,p2,p3,zf,zz,s,t,q,r,u,v,e,f,c,d,w,a1,gn;
    long l,lbin,av,av1,av2,k,l1,n,ex;
  
    if (typ(gx)!=t_REAL)
      { l=prec; k=1; }
--- 115,132 ----
  /**                                                                   **/
  /***********************************************************************/
  
! /* Assume gx > 0 and a,b complex */
! /* This might one day be extended to handle complex gx */
! /* see Temme, N. M. "The numerical computation of the confluent        */
! /* hypergeometric function U(a,b,z)" in Numer. Math. 41 (1983),        */
! /* no. 1, 63--82.                                                      */
  GEN
  hyperu(GEN a, GEN b, GEN gx, long prec)
  {
    GEN x,y,p1,p2,p3,zf,zz,s,t,q,r,u,v,e,f,c,d,w,a1,gn;
    long l,lbin,av,av1,av2,k,l1,n,ex;
+ 
+   if(gsigne(gx) <= 0) err(talker,"hyperu's third argument must be positive");
  
    if (typ(gx)!=t_REAL)
      { l=prec; k=1; }
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