debugger

   echo = 1
? default(breakloop,1)
? my(bound=100,step=20,halt=41);check(B)=my(bi=[B^2]);for(i=1,bound,my(p=i+step,N=p^2);if(i==halt,error("check:",N)))
(B)->my(bound=100,step=20,halt=41);my(bi=[B^2]);for(i=1,bound,my(p=i+step,N=
p^2);if(i==halt,error("check:",N)))
? check(1000);
  ***   at top-level: check(1000)
  ***                 ^-----------
  ***   in function check: ...i+step,N=p^2);if(i==halt,error("check:",N)))
  ***                                                  ^-------------------
  ***   user error: check:3721
  ***   Break loop: type 'break' to go back to GP prompt
break> [bound,step,halt,i,p,N,bi,B]
[100, 20, 41, 41, 61, 3721, [1000000], 1000]
break> break

? [bound,step,halt,i,p,N,bi,B]
[bound, step, halt, i, p, N, bi, B]
? my(p=120);for(i=1,100,1/0)
  ***   at top-level: my(p=120);for(i=1,100,1/0)
  ***                                        ^---
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break> [p,i]
[120, 1]
break> dbg_err()
error("impossible inverse in gdiv: 0.")
break> break

? fun(N)=check(N^2+1);
? fun(20);
  ***   at top-level: fun(20)
  ***                 ^-------
  ***   in function fun: check(N^2+1)
  ***                    ^------------
  ***   in function check: ...i+step,N=p^2);if(i==halt,error("check:",N)))
  ***                                                  ^-------------------
  ***   user error: check:3721
  ***   Break loop: type 'break' to go back to GP prompt
break> N
3721
break> dbg_up(4)
  ***   at top-level: fun(20)
  ***                 ^-------
  ***   in function fun: check(N^2+1)
  ***                    ^------------
break> N
20
break> dbg_down(4)
  ***   at top-level: fun(20)
  ***                 ^-------
  ***   in function fun: check(N^2+1)
  ***                    ^------------
  ***   in function check: ...i+step,N=p^2);if(i==halt,error("check:",N)))
  ***                                                  ^-------------------
break> N
3721
break> break

? f(N,x)=my(z=x^2+1);breakpoint();gcd(N,z^2+1-z);
? f(221,3)
  ***   at top-level: f(221,3)
  ***                 ^--------
  ***   in function f: my(z=x^2+1);breakpoint();gcd(N,z^2+1-z)
  ***                              ^---------------------------

  ***   Break loop: <Return> to continue; 'break' to go back to GP prompt
break> z
10
13
? z
z
? iferrname("e_VAR",vector(10000,i,1/(i-100)),E,Vec(E))
  ***   at top-level: ...("e_VAR",vector(10000,i,1/(i-100)),E,Vec(E))
  ***                                             ^-------------------
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break> i
100
break> break

? f()=1/0
()->1/0
? f();
  ***   at top-level: f()
  ***                 ^---
  ***   in function f: 1/0
  ***                   ^--
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break> allocatemem(10^7)
  ***   Warning: new stack size = 10000000 (9.537 Mbytes).
? for(i=1,10,if(i==2,1/0));
  ***   at top-level: for(i=1,10,if(i==2,1/0))
  ***                                     ^----
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break> i
2
break> N=5
5
break> M=6;1/0
  ***   at top-level: for(i=1,10,if(i==2,1/0))
  ***                                     ^----
  ***   in anonymous function: M=6;1/0
  ***                               ^--
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break[2]> break

  ***   at top-level: for(i=1,10,if(i==2,1/0))
  ***                                     ^----
break> N
5
break> M
M
break> break

? F1(T)=1/0;
? F1(2)
  ***   at top-level: F1(2)
  ***                 ^-----
  ***   in function F1: 1/0
  ***                    ^--
  *** _/_: impossible inverse in gdiv: 0.
  ***   Break loop: type 'break' to go back to GP prompt
break> dbg_up
  ***   at top-level: F1(2)
  ***                 ^-----
break> T
T
break> break

? print("Total time spent: ",gettime);
Total time spent: 1