PARI's commands

[science_man_88]

Originally Posted by science_man_88

 
a=[1,2,3];b=#a;until(#a==1,a[1]=concat(Str(a[1]),Str(a[2]));if(#a==b,a[b-1]=a[b]);a=vector(#a-1,n,a[n]));a=eval(a[1])

the correct version is:

a=[1,3,7,15,31,63];until(#a==1,a[1]=concat(Str(a[1]),Str(a[2]));for(b=3,#a,a[b-1]=a[b]);a=vector(#a-1,n,a[n]));a=eval(a[1])

[ismillo]

Thank you very much, Sir. This will help a lot.
PARI is a great languague for mathematics no doubts, however let's be honest, it's some times so much complicated.

For anyone who has the same problem I had, here is the function, only if you may, science_man_88, all credits for you.

vectoint(a)={
	until(#a==1,a[1]=concat(Str(a[1]),Str(a[2]));for(b=3,#a,a[b-1]=a[b]);
	a=vector(#a-1,n,a[n]));
	a=eval(a[1])
};

Once again, thank you very much, for solving my problem and for quick reply as well.

[axn]

vec2int(a)={my(s=""); for(i=1,#a,s=Str(s,a[i])); eval(s)}

[ismillo]

Another great help, axn, thank you.

I was doing some test here, axn is a faster, however, both are excellent and helps a lot.

[CRGreathouse]

There's an even faster version available if your numbers are only a digit each:

subst(Pol(a), 'x, 10)

[ismillo]

Awesome, this will help a lot with large palindromics numbers.
I usually compare palindromes making vectors and never knew how I could manipulate the numbers.

Edit:
One last question, how do I return the position of a specific character from a word?
For example 'a = "ABC"' and return "A".

PS.: I know PARI isn't the right language for strings, but in the end, it's all about Mathematics.

[CRGreathouse]

Originally Posted by ismillo

One last question, how do I return the position of a specific character from a word?
For example 'a = "ABC"' and return "A".

PS.: I know PARI isn't the right language for strings, but in the end, it's all about Mathematics.

PARI is bad at this. The best method it has to offer is Vec("ABC")[1]. For finding a string, you can try

find(source, target)={
  source=Vec(source);
  target=Vec(target);
  for(i=0,#source-#target,
    for(j=1,#target,
      if(target[j]!=source[i+j],next(2))
    );
    return(i+1)
  );
  -1
};

[CRGreathouse]

Originally Posted by ismillo

Awesome, this will help a lot with large palindromics numbers.
I usually compare palindromes making vectors and never knew how I could manipulate the numbers.

I should also mention the commands Vecrev and Polrev, then.

subst(Polrev(digits(123)), 'x, 10)

gives 321.

[ismillo]

Originally Posted by CRGreathouse

I should also mention the commands Vecrev and Polrev, then.

subst(Polrev(digits(123)), 'x, 10)

gives 321.

Nice, I didn't knew I could reverse vector with function from PARI, so I made my own. :D

Originally Posted by CRGreathouse

PARI is bad at this. The best method it has to offer is Vec("ABC")[1]. For finding a string, you can try

find(source, target)={
  source=Vec(source);
  target=Vec(target);
  for(i=0,#source-#target,
    for(j=1,#target,
      if(target[j]!=source[i+j],next(2))
    );
    return(i+1)
  );
  -1
};

This is perfect, I guess. Later I will give it a shot, if I succeed then I notify you guys.

[ismillo]

Well, I'm having an issue with 2 equal letters, I'll keep trying, if can't do it I will try make in C.
:/

[CRGreathouse]

Originally Posted by ismillo

Well, I'm having an issue with 2 equal letters, I'll keep trying, if can't do it I will try make in C.
:/

Can you give an example of the input, the expected output, and the actual output? I'll admit that I didn't test my script at all, just typed it up, so bugs are certainly possible.