Opened 14 years ago

Closed 14 years ago

# description of farey starts with factorize

Reported by: Owned by: gorzel somebody trivial 3-1-1 doc 3-1-0

### Description

The description of farey on

Singular/3-1-0/html/sing_197.htm#SEC238

starts with factorize

```
5.1.31 farey

Syntax:
factorize ( poly_expression )
factorize ( poly_expression, 0 )
factorize ( poly_expression, 2 )
Type:
list of ideal and intvec
Syntax:
farey ( bigint_expression, bigint_expression )
farey ( ideal_expression, bigint_expression )
Type:
number/ideal
Purpose:
lift the first argument modulo the second to the rationals
Note:
The current coefficient field must be the rationals.
Example:

ring r=0,x,dp;
farey(2,32003);
==> 2

```

An other example showing that really something is happing may be more useful.

### comment:1 Changed 14 years ago by hannes

Resolution: → fixed new → closed

### comment:2 Changed 14 years ago by gorzel

Resolution: fixed closed → reopened

Now you have changed three time factorize to farey. This is likewise wrong. Just erase the first five lines, the correct description of the command is already found in the subsequent lines!

To be explicit: This

```Syntax:
factorize ( poly_expression )
factorize ( poly_expression, 0 )
factorize ( poly_expression, 2 )
Type:
list of ideal and intvec
```

was changed to

```Syntax:
farey ( poly_expression )
farey ( poly_expression, 0 )
farey ( poly_expression, 2 )
Type:
list of ideal and intvec
```

but these lines have to be killed!

And once again: A better example, and also one for farey ( ideal_expression, bigint_expression ) would be useful.

```> farey(bigint(7),bigint(32));
3/5
> typeof(_);
number
> farey(ideal(5/3x,3/7y),32);
_[1]=-1/3x
_[2]=3y
> typeof(_);
ideal
```

Finally, it seems that farey also works in other non-documented cases:

```> ring r=0,(x,y,z),dp;
> farey(13/4,320);   //  farey(number,bigint);
_[1,1]=-1/3
> typeof(_);         // return type matrix should be number instead
matrix

> matrix M[2][2] = 1/3,2/5,3/7,x;
> farey(M,32);                         // farey(matrix,bigint);
_[1]=3*gen(2)+gen(1)
_[2]=x*gen(2)+2*gen(1)
> typeof(_);                           // return type module, but it should be matrix again?!
module

> farey(module(M),32);                 // farey(module,bigint);
_[1]=3*gen(2)+gen(1)
_[2]=x*gen(2)+2*gen(1)
> typeof(_);                           // return type module
module
```

### comment:3 Changed 14 years ago by hannes

Resolution: → fixed reopened → closed

no, description fixed in the correct way

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