Returns a string built from the remaining arguments according to the
format fmt. The format consists of ordinary characters (not %), printed
unchanged, and conversions specifications. See printf
.
Changes the help message for the symbol sym
. The string str
is expanded on the spot and stored as the online help for sym
. It is
recommended to document global variables and user functions in this way,
although gp
will not protest if you don't.
You can attach a help text to an alias, but it will never be
shown: aliases are expanded by the ?
help operator and we get the help
of the symbol the alias points to. Nothing prevents you from modifying the
help of built-in PARI functions. But if you do, we would like to hear why you
needed it!
Without addhelp
, the standard help for user functions consists of its
name and definition.
gp> f(x) = x^2; gp> ?f f = (x)->x^2Once addhelp is applied to f, the function code is no longer included. It can still be consulted by typing the function name:
gp> addhelp(f, "Square") gp> ?f Square gp> f %2 = (x)->x^2
The library syntax is void addhelp(const char *sym, const char *str)
.
If code is omitted, trigger an e_ALARM exception after s seconds, cancelling any previously set alarm; stop a pending alarm if s = 0 or is omitted.
Otherwise, if s is positive, the function evaluates code,
aborting after s seconds. The return value is the value of code if
it ran to completion before the alarm timeout, and a t_ERROR
object
otherwise.
? p = nextprime(10^25); q = nextprime(10^26); N = p*q; ? E = alarm(1, factor(N)); ? type(E) %3 = "t_ERROR" ? print(E) %4 = error("alarm interrupt after 964 ms.") ? alarm(10, factor(N)); \\ enough time %5 = [ 10000000000000000000000013 1] [100000000000000000000000067 1]Here is a more involved example: the function
timefact(N,sec)
below tries to factor N and gives up after sec
seconds, returning a partial factorisation.
\\ Time-bounded partial factorization default(factor_add_primes,1); timefact(N,sec)= { F = alarm(sec, factor(N)); if (type(F) == "t_ERROR", factor(N, 2^24), F); }We either return the factorization directly, or replace the
t_ERROR
result by a simple bounded factorization factor(N, 2^24)
.
Note the factor_add_primes
trick: any prime larger than 2^{24}
discovered while attempting the initial factorization is stored and
remembered. When the alarm rings, the subsequent bounded factorization finds
it right away.
Caveat. It is not possible to set a new alarm within
another alarm
code: the new timer erases the parent one.
Defines the symbol newsym as an alias for the the symbol sym:
? alias("det", "matdet"); ? det([1,2;3,4]) %1 = -2
You are not restricted to ordinary functions, as in the above example:
to alias (from/to) member functions, prefix them with `_.
';
to alias operators, use their internal name, obtained by writing
_
in lieu of the operators argument: for instance, _!
and
!_
are the internal names of the factorial and the
logical negation, respectively.
? alias("mod", "_.mod"); ? alias("add", "_+_"); ? alias("_.sin", "sin"); ? mod(Mod(x,x^4+1)) %2 = x^4 + 1 ? add(4,6) %3 = 10 ? Pi.sin %4 = 0.E-37
Alias expansion is performed directly by the internal GP compiler. Note that since alias is performed at compilation-time, it does not require any run-time processing, however it only affects GP code compiled after the alias command is evaluated. A slower but more flexible alternative is to use variables. Compare
? fun = sin; ? g(a,b) = intnum(t=a,b,fun(t)); ? g(0, Pi) %3 = 2.0000000000000000000000000000000000000 ? fun = cos; ? g(0, Pi) %5 = 1.8830410776607851098 E-39
with
? alias(fun, sin); ? g(a,b) = intnum(t=a,b,fun(t)); ? g(0,Pi) %2 = 2.0000000000000000000000000000000000000 ? alias(fun, cos); \\ Oops. Does not affect *previous* definition! ? g(0,Pi) %3 = 2.0000000000000000000000000000000000000 ? g(a,b) = intnum(t=a,b,fun(t)); \\ Redefine, taking new alias into account ? g(0,Pi) %5 = 1.8830410776607851098 E-39
A sample alias file misc/gpalias
is provided with
the standard distribution.
The library syntax is void alias0(const char *newsym, const char *sym)
.
This special operation changes the stack size after initialization. x must be a non-negative integer. If x > 0, a new stack of at least x bytes is allocated. We may allocate more than x bytes if x is way too small, or for alignment reasons: the current formula is \max(16*ceil{x/16}, 500032) bytes.
If x = 0, the size of the new stack is twice the size of the old one. The old stack is discarded.
Warning. This function should be typed at the gp
prompt in
interactive usage, or left by itself at the start of batch files.
It cannot be used meaningfully in loop-like constructs, or as part of a
larger expression sequence, e.g
allocatemem(); x = 1; \\ This will not set x
!
In fact, all loops are immediately exited, user functions terminated, and
the rest of the sequence following allocatemem()
is silently
discarded, as well as all pending sequences of instructions. We just go on
reading the next instruction sequence from the file we're in (or from the
user). In particular, we have the following possibly unexpected behavior: in
read("file.gp"); x = 1were
file.gp
contains an allocatemem
statement,
the x = 1
is never executed, since all pending instructions in the
current sequence are discarded.
The technical reason is that this routine moves the stack, so temporary
objects created during the current expression evaluation are not correct
anymore. (In particular byte-compiled expressions, which are allocated on
the stack.) To avoid accessing obsolete pointers to the old stack, this
routine ends by a longjmp
.
Remark. If the operating system cannot allocate the desired x bytes, a loop halves the allocation size until it succeeds:
? allocatemem(5*10^10) *** Warning: not enough memory, new stack 50000000000. *** Warning: not enough memory, new stack 25000000000. *** Warning: not enough memory, new stack 12500000000. *** Warning: new stack size = 6250000000 (5960.464 Mbytes).
Apply the t_CLOSURE
f
to the entries of A
. If A
is a scalar, return f(A)
. If A
is a polynomial or power series,
apply f
on all coefficients. If A
is a vector or list, return
the elements f(x) where x runs through A
. If A
is a matrix,
return the matrix whose entries are the f(A[i,j]
).
? apply(x->x^2, [1,2,3,4]) %1 = [1, 4, 9, 16] ? apply(x->x^2, [1,2;3,4]) %2 = [1 4] [9 16] ? apply(x->x^2, 4*x^2 + 3*x+ 2) %3 = 16*x^2 + 9*x + 4Note that many functions already act componentwise on vectors or matrices, but they almost never act on lists; in this case,
apply
is a good solution:
? L = List([Mod(1,3), Mod(2,4)]); ? lift(L) *** at top-level: lift(L) *** ^------- *** lift: incorrect type in lift. ? apply(lift, L); %2 = List([1, 2])
Remark. For v a t_VEC
, t_COL
, t_LIST
or t_MAT
,
the alternative set-notations
[g(x) | x <- v, f(x)] [x | x <- v, f(x)] [g(x) | x <- v]
are available as shortcuts for
apply(g, select(f, Vec(v))) select(f, Vec(v)) apply(g, Vec(v))respectively:
? L = List([Mod(1,3), Mod(2,4)]); ? [ lift(x) | x<-L ] %2 = [1, 2]
The library syntax is genapply(void *E, GEN (*fun)(void*,GEN), GEN a)
.
Returns the default corresponding to keyword key. If val is
present, sets the default to val first (which is subject to string
expansion first). Typing default()
(or \d
) yields the complete
default list as well as their current values. See Section [Label: se:defaults] for an
introduction to GP defaults, Section [Label: se:gp_defaults] for a
list of available defaults, and Section [Label: se:meta] for some shortcut
alternatives. Note that the shortcuts are meant for interactive use and
usually display more information than default
.
The library syntax is GEN default0(const char *key = NULL, const char *val = NULL)
.
Returns the type of the error message E
as a string.
The library syntax is GEN errname(GEN E)
.
Outputs its argument list (each of
them interpreted as a string), then interrupts the running gp
program,
returning to the input prompt. For instance
error("n = ", n, " is not squarefree!")
The string str is the name of an external command (i.e. one you
would type from your UNIX shell prompt). This command is immediately run and
its output fed into gp
, just as if read from a file.
The string str is the name of an external command (i.e. one you would type from your UNIX shell prompt). This command is immediately run and its output is returned as a vector of GP strings, one component per output line.
Returns the time (in milliseconds) elapsed since gp
startup. This
provides a reentrant version of gettime
:
my (t = getabstime()); ... print("Time: ", getabstime() - t);
The library syntax is long getabstime()
.
Return the value of the environment variable s
if it is defined, otherwise return 0.
The library syntax is GEN gp_getenv(const char *s)
.
Returns a two-component row vector giving the number of objects on the heap and the amount of memory they occupy in long words. Useful mainly for debugging purposes.
The library syntax is GEN getheap()
.
Returns the current value of the seed used by the
pseudo-random number generator random
. Useful mainly for debugging
purposes, to reproduce a specific chain of computations. The returned value
is technical (reproduces an internal state array), and can only be used as an
argument to setrand
.
The library syntax is GEN getrand()
.
Returns the current value of top
-avma
, i.e. the number of
bytes used up to now on the stack. Useful mainly for debugging purposes.
The library syntax is long getstack()
.
Returns the time (in milliseconds) elapsed since either the last call to
gettime
, or to the beginning of the containing GP instruction (if
inside gp
), whichever came last.
For a reentrant version, see getabstime
.
The library syntax is long gettime()
.
Obsolete. Scheduled for deletion.
(Experimental) declare x,..., z as inline variables. Such variables
behave like lexically scoped variable (see my()) but with unlimited scope.
It is however possible to exit the scope by using uninline()
.
When used in a GP script, it is recommended to call uninline()
before
the script's end to avoid inline variables leaking outside the script.
Reads a string, interpreted as a GP expression,
from the input file, usually standard input (i.e. the keyboard). If a
sequence of expressions is given, the result is the result of the last
expression of the sequence. When using this instruction, it is useful to
prompt for the string by using the print1
function. Note that in the
present version 2.19 of pari.el
, when using gp
under GNU Emacs (see
Section [Label: se:emacs]) one must prompt for the string, with a string
which ends with the same prompt as any of the previous ones (a "? "
will do for instance).
Loads from dynamic library lib the function name. Assigns to it
the name gpname in this gp
session, with prototype
code (see below). If gpname is omitted, uses name.
If lib is omitted, all symbols known to gp
are available: this
includes the whole of libpari.so
and possibly others (such as
libc.so
).
Most importantly, install
gives you access to all non-static functions
defined in the PARI library. For instance, the function \kbd{GEN addii(GEN
x, GEN y)} adds two PARI integers, and is not directly accessible under
gp
(it is eventually called by the +
operator of course):
? install("addii", "GG") ? addii(1, 2) %1 = 3
It also allows to add external functions to the gp
interpreter.
For instance, it makes the function system
obsolete:
? install(system, vs, sys,/*omitted*/) ? sys("ls gp*") gp.c gp.h gp_rl.cThis works because
system
is part of libc.so
,
which is linked to gp
. It is also possible to compile a shared library
yourself and provide it to gp in this way: use gp2c
, or do it manually
(see the modules_build
variable in pari.cfg
for hints).
Re-installing a function will print a warning and update the prototype code if needed. However, it will not reload a symbol from the library, even if the latter has been recompiled.
Prototype. We only give a simplified description here, covering
most functions, but there are many more possibilities. The full documentation
is available in libpari.dvi
, see
??prototype
* First character i
, l
, v
: return type int / long /
void. (Default: GEN
)
* One letter for each mandatory argument, in the same order as they appear
in the argument list: G
(GEN
), &
(GEN*
), L
(long
), s
(char *
), n
(variable).
* p
to supply realprecision
(usually long prec
in the
argument list), P
to supply seriesprecision
(usually \kbd{long
precdl}).
We also have special constructs for optional arguments and default values:
* DG
(optional GEN
, NULL
if omitted),
* D&
(optional GEN*
, NULL
if omitted),
* Dn
(optional variable, -1 if omitted),
For instance the prototype corresponding to
long issquareall(GEN x, GEN *n = NULL)is
lGD&
.
Caution. This function may not work on all systems, especially
when gp
has been compiled statically. In that case, the first use of an
installed function will provoke a Segmentation Fault (this should never
happen with a dynamically linked executable). If you intend to use this
function, please check first on some harmless example such as the one above
that it works properly on your machine.
The library syntax is void gpinstall(const char *name, const char *code, const char *gpname, const char *lib)
.
Restores the symbol sym
to its "undefined" status, and deletes any
help messages associated to sym
using addhelp
. Variable names
remain known to the interpreter and keep their former priority: you cannot
make a variable "less important" by killing it!
? z = y = 1; y %1 = 1 ? kill(y) ? y \\ restored to ``undefined'' status %2 = y ? variable() %3 = [x, y, z] \\ but the variable name y is still known, with y > z !
For the same reason, killing a user function (which is an ordinary
variable holding a t_CLOSURE
) does not remove its name from the list of
variable names.
If the symbol is associated to a variable --- user functions being an
important special case ---, one may use the quote operator
a = 'a
to reset variables to their starting values. However, this
will not delete a help message associated to a
, and is also slightly
slower than kill(a)
.
? x = 1; addhelp(x, "foo"); x %1 = 1 ? x = 'x; x \\ same as 'kill', except we don't delete help. %2 = x ? ?x foo
On the other hand, kill
is the only way to remove aliases and installed
functions.
? alias(fun, sin); ? kill(fun); ? install(addii, GG); ? kill(addii);
The library syntax is void kill0(const char *sym)
.
Outputs its (string) arguments in raw format, ending with a newline.
Outputs its (string) arguments in raw
format, without ending with a newline. Note that you can still embed newlines
within your strings, using the \n
notation !
This function is based on the C library command of the same name. It prints its arguments according to the format fmt, which specifies how subsequent arguments are converted for output. The format is a character string composed of zero or more directives:
* ordinary characters (not %
), printed unchanged,
* conversions specifications (%
followed by some characters)
which fetch one argument from the list and prints it according to the
specification.
More precisely, a conversion specification consists in a %
, one or more
optional flags (among #
, 0
, -
, +
, ` '), an optional
decimal digit string specifying a minimal field width, an optional precision
in the form of a period (`.
') followed by a decimal digit string, and
the conversion specifier (among d
,i
, o
, u
,
x
,X
, p
, e
,E
, f
, g
,G
, s
).
The flag characters. The character %
is followed by zero or
more of the following flags:
* #
: The value is converted to an "alternate form". For
o
conversion (octal), a 0
is prefixed to the string. For x
and X
conversions (hexa), respectively 0x
and 0X
are
prepended. For other conversions, the flag is ignored.
* 0
: The value should be zero padded. For
d
,
i
,
o
,
u
,
x
,
X
e
,
E
,
f
,
F
,
g
, and
G
conversions, the value is padded on the left with zeros rather than
blanks. (If the 0
and -
flags both appear, the 0
flag is
ignored.)
* -
: The value is left adjusted on the field boundary. (The
default is right justification.) The value is padded on the right with
blanks, rather than on the left with blanks or zeros. A -
overrides a
0
if both are given.
* ` '
(a space): A blank is left before a positive number
produced by a signed conversion.
* +
: A sign (+ or -) is placed before a number produced by a
signed conversion. A +
overrides a space if both are used.
The field width. An optional decimal digit string (whose first
digit is non-zero) specifying a minimum field width. If the value has
fewer characters than the field width, it is padded with spaces on the left
(or right, if the left-adjustment flag has been given). In no case does a
small field width cause truncation of a field; if the value is wider than
the field width, the field is expanded to contain the conversion result.
Instead of a decimal digit string, one may write *
to specify that the
field width is given in the next argument.
The precision. An optional precision in the form of a period
(`.
') followed by a decimal digit string. This gives
the number of digits to appear after the radix character for e
,
E
, f
, and F
conversions, the maximum number of significant
digits for g
and G
conversions, and the maximum number of
characters to be printed from an s
conversion.
Instead of a decimal digit string, one may write *
to specify that the
field width is given in the next argument.
The length modifier. This is ignored under gp
, but
necessary for libpari
programming. Description given here for
completeness:
* l
: argument is a long
integer.
* P
: argument is a GEN
.
The conversion specifier. A character that specifies the type of conversion to be applied.
* d
, i
: A signed integer.
* o
, u
, x
, X
: An unsigned integer, converted
to unsigned octal (o
), decimal (u
) or hexadecimal (x
or
X
) notation. The letters abcdef
are used for x
conversions; the letters ABCDEF
are used for X
conversions.
* e
, E
: The (real) argument is converted in the style
[ -]d.ddd e[ -]dd
, where there is one digit before the decimal point,
and the number of digits after it is equal to the precision; if the
precision is missing, use the current realprecision
for the total
number of printed digits. If the precision is explicitly 0, no decimal-point
character appears. An E
conversion uses the letter E
rather
than e
to introduce the exponent.
* f
, F
: The (real) argument is converted in the style
[ -]ddd.ddd
, where the number of digits after the decimal point
is equal to the precision; if the precision is missing, use the current
realprecision
for the total number of printed digits. If the precision
is explicitly 0, no decimal-point character appears. If a decimal point
appears, at least one digit appears before it.
* g
, G
: The (real) argument is converted in style
e
or f
(or E
or F
for G
conversions)
[ -]ddd.ddd
, where the total number of digits printed
is equal to the precision; if the precision is missing, use the current
realprecision
. If the precision is explicitly 0, it is treated as 1.
Style e
is used when
the decimal exponent is < -4, to print 0.
, or when the integer
part cannot be decided given the known significant digits, and the f
format otherwise.
* c
: The integer argument is converted to an unsigned char, and the
resulting character is written.
* s
: Convert to a character string. If a precision is given, no
more than the specified number of characters are written.
* p
: Print the address of the argument in hexadecimal (as if by
%#x
).
* %
: A %
is written. No argument is converted. The complete
conversion specification is %%
.
Examples:
? printf("floor: %d, field width 3: %3d, with sign: %+3d\n", Pi, 1, 2); floor: 3, field width 3: 1, with sign: +2 ? printf("%.5g %.5g %.5g\n",123,123/456,123456789); 123.00 0.26974 1.2346 e8 ? printf("%-2.5s:%2.5s:%2.5s\n", "P", "PARI", "PARIGP"); P :PARI:PARIG \\ min field width and precision given by arguments ? x = 23; y=-1/x; printf("x=%+06.2f y=%+0*.*f\n", x, 6, 2, y); x=+23.00 y=-00.04 \\ minimum fields width 5, pad left with zeroes ? for (i = 2, 5, printf("%05d\n", 10^i)) 00100 01000 10000 100000 \\ don't truncate fields whose length is larger than the minimum width ? printf("%.2f |%06.2f|", Pi,Pi) 3.14 | 3.14|All numerical conversions apply recursively to the entries of vectors and matrices:
? printf("%4d", [1,2,3]); [ 1, 2, 3] ? printf("%5.2f", mathilbert(3)); [ 1.00 0.50 0.33] [ 0.50 0.33 0.25] [ 0.33 0.25 0.20]
Technical note. Our implementation of printf
deviates from the C89 and C99 standards in a few places:
* whenever a precision is missing, the current realprecision
is
used to determine the number of printed digits (C89: use 6 decimals after
the radix character).
* in conversion style e
, we do not impose that the
exponent has at least two digits; we never write a +
sign in the
exponent; 0 is printed in a special way, always as 0.Eexp
.
* in conversion style f
, we switch to style e
if the
exponent is greater or equal to the precision.
* in conversion g
and G
, we do not remove trailing zeros
from the fractional part of the result; nor a trailing decimal point;
0 is printed in a special way, always as 0.Eexp
.
Outputs its (string) arguments in raw format, ending with a newline. Successive entries are separated by sep:
? printsep(":", 1,2,3,4) 1:2:3:4
Outputs its (string) arguments in raw format, without ending with a newline. Successive entries are separated by sep:
? printsep1(":", 1,2,3,4);print("|") 1:2:3:4
Outputs its (string) arguments in TeX format. This output can then be
used in a TeX manuscript.
The printing is done on the standard output. If you want to print it to a
file you should use writetex
(see there).
Another possibility is to enable the log
default
(see Section [Label: se:defaults]).
You could for instance do:
default(logfile, "new.tex"); default(log, 1); printtex(result);
Exits gp
and return to the system with exit status
status
, a small integer. A non-zero exit status normally indicates
abnormal termination. (Note: the system actually sees only
status
mod 256, see your man pages for exit(3)
or wait(2)
).
Reads in the file
filename (subject to string expansion). If filename is
omitted, re-reads the last file that was fed into gp
. The return
value is the result of the last expression evaluated.
If a GP binary file
is read using this command (see
Section [Label: se:writebin]), the file is loaded and the last object in the file
is returned.
In case the file you read in contains an allocatemem
statement (to be
generally avoided), you should leave read
instructions by themselves,
and not part of larger instruction sequences.
Reads in the file filename and return a vector of GP strings,
each component containing one line from the file. If filename is
omitted, re-reads the last file that was fed into gp
.
Reads in the file
filename (subject to string expansion). If filename is
omitted, re-reads the last file that was fed into gp
. The return
value is a vector whose components are the evaluation of all sequences
of instructions contained in the file. For instance, if file contains
1 2 3
then we will get:
? \r a %1 = 1 %2 = 2 %3 = 3 ? read(a) %4 = 3 ? readvec(a) %5 = [1, 2, 3]
In general a sequence is just a single line, but as usual braces and
\
may be used to enter multiline sequences.
The library syntax is GEN gp_readvec_file(const char *filename)
.
The underlying library function
GEN gp_readvec_stream(FILE *f)
is usually more flexible.
We first describe the default behaviour, when flag is 0 or omitted.
Given a vector or list A
and a t_CLOSURE
f
, select
returns the elements x of A
such that f(x) is non-zero. In other
words, f
is seen as a selection function returning a boolean value.
? select(x->isprime(x), vector(50,i,i^2+1)) %1 = [2, 5, 17, 37, 101, 197, 257, 401, 577, 677, 1297, 1601] ? select(x->(x<100), %) %2 = [2, 5, 17, 37]returns the primes of the form i^2+1 for some i
<=
50,
then the elements less than 100 in the preceding result. The select
function also applies to a matrix A
, seen as a vector of columns, i.e. it
selects columns instead of entries, and returns the matrix whose columns are
the selected ones.
Remark. For v a t_VEC
, t_COL
, t_LIST
or t_MAT
,
the alternative set-notations
[g(x) | x <- v, f(x)] [x | x <- v, f(x)] [g(x) | x <- v]
are available as shortcuts for
apply(g, select(f, Vec(v))) select(f, Vec(v)) apply(g, Vec(v))respectively:
? [ x | x <- vector(50,i,i^2+1), isprime(x) ] %1 = [2, 5, 17, 37, 101, 197, 257, 401, 577, 677, 1297, 1601]
If flag = 1, this function returns instead the indices of the selected elements, and not the elements themselves (indirect selection):
? V = vector(50,i,i^2+1); ? select(x->isprime(x), V, 1) %2 = Vecsmall([1, 2, 4, 6, 10, 14, 16, 20, 24, 26, 36, 40]) ? vecextract(V, %) %3 = [2, 5, 17, 37, 101, 197, 257, 401, 577, 677, 1297, 1601]
The following function lists the elements in (Z/NZ)^*:
? invertibles(N) = select(x->gcd(x,N) == 1, [1..N])
Finally
? select(x->x, M)selects the non-0 entries in
M
. If the latter is a
t_MAT
, we extract the matrix of non-0 columns. Note that removing
entries instead of selecting them just involves replacing the selection
function f
with its negation:
? select(x->!isprime(x), vector(50,i,i^2+1))
The library syntax is genselect(void *E, long (*fun)(void*,GEN), GEN a)
. Also available
is GEN genindexselect(void *E, long (*fun)(void*, GEN), GEN a)
,
corresponding to flag = 1.
Reseeds the random number generator using the seed n. No value is
returned. The seed is either a technical array output by getrand
, or a
small positive integer, used to generate deterministically a suitable state
array. For instance, running a randomized computation starting by
setrand(1)
twice will generate the exact same output.
The library syntax is void setrand(GEN n)
.
str is a string representing a system command. This command is
executed, its output written to the standard output (this won't get into your
logfile), and control returns to the PARI system. This simply calls the C
system
command.
THIS FUNCTION IS OBSOLETE: use iferr
, which has a nicer and much
more powerful interface. For compatibility's sake we now describe the
obsolete function trap
.
This function tries to
evaluate seq, trapping runtime error e, that is effectively preventing
it from aborting computations in the usual way; the recovery sequence
rec is executed if the error occurs and the evaluation of rec
becomes the result of the command. If e is omitted, all exceptions are
trapped. See Section [Label: se:errorrec] for an introduction to error recovery
under gp
.
? \\ trap division by 0 ? inv(x) = trap (e_INV, INFINITY, 1/x) ? inv(2) %1 = 1/2 ? inv(0) %2 = INFINITY
Note that seq is effectively evaluated up to the point that produced the error, and the recovery sequence is evaluated starting from that same context, it does not "undo" whatever happened in the other branch (restore the evaluation context):
? x = 1; trap (, /* recover: */ x, /* try: */ x = 0; 1/x) %1 = 0
Note. The interface is currently not adequate for trapping
individual exceptions. In the current version 2.7.0, the following keywords
are recognized, but the name list will be expanded and changed in the
future (all library mode errors can be trapped: it's a matter of defining
the keywords to gp
):
e_ALARM
: alarm time-out
e_ARCH
: not available on this architecture or operating system
e_STACK
: the PARI stack overflows
e_INV
: impossible inverse
e_IMPL
: not yet implemented
e_OVERFLOW
: all forms of arithmetic overflow, including length
or exponent overflow (when a larger value is supplied than the
implementation can handle).
e_SYNTAX
: syntax error
e_MISC
: miscellaneous error
e_TYPE
: wrong type
e_USER
: user error (from the error
function)
The library syntax is GEN trap0(const char *e = NULL, GEN rec = NULL, GEN seq = NULL)
.
This is useful only under gp
. Returns the internal type name of
the PARI object x as a string. Check out existing type names with the
metacommand \t
. For example type(1)
will return "t_INT
".
The library syntax is GEN type0(GEN x)
.
The macro typ
is usually simpler to use since it returns a
long
that can easily be matched with the symbols t_*
. The name
type
was avoided since it is a reserved identifier for some compilers.
(Experimental) Exit the scope of all current inline
variables.
Returns the current version number as a t_VEC
with three integer
components (major version number, minor version number and patchlevel);
if your sources were obtained through our version control system, this will
be followed by further more precise arguments, including
e.g. a git
commit hash.
This function is present in all versions of PARI following releases 2.3.4 (stable) and 2.4.3 (testing).
Unless you are working with multiple development versions, you probably only
care about the 3 first numeric components. In any case, the lex
function
offers a clever way to check against a particular version number, since it will
compare each successive vector entry, numerically or as strings, and will not
mind if the vectors it compares have different lengths:
if (lex(version(), [2,3,5]) >= 0, \\ code to be executed if we are running 2.3.5 or more recent. , \\ compatibility code );On a number of different machines,
version()
could return either of
%1 = [2, 3, 4] \\ released version, stable branch %1 = [2, 4, 3] \\ released version, testing branch %1 = [2, 6, 1, 15174, ""505ab9b"] \\ development
In particular, if you are only working with released versions, the first line of the gp introductory message can be emulated by
[M,m,p] = version(); printf("GP/PARI CALCULATOR Version %s.%s.%s", M,m,p);If you are working with many development versions of PARI/GP, the 4th and/or 5th components can be profitably included in the name of your logfiles, for instance.
Technical note. For development versions obtained via git
,
the 4th and 5th components are liable to change eventually, but we document
their current meaning for completeness. The 4th component counts the number
of reachable commits in the branch (analogous to svn
's revision
number), and the 5th is the git
commit hash. In particular, lex
comparison still orders correctly development versions with respect to each
others or to released versions (provided we stay within a given branch,
e.g. master
)!
The library syntax is GEN pari_version()
.
Outputs the message "user warning" and the argument list (each of them interpreted as a string). If colors are enabled, this warning will be in a different color, making it easy to distinguish.
warning(n, " is very large, this might take a while.")
If keyword key is the name of a function that was present in GP version 1.39.15 or lower, outputs the new function name and syntax, if it changed at all (387 out of 560 did).
Writes (appends) to filename the remaining arguments, and appends a
newline (same output as print
).
Writes (appends) to filename the remaining arguments without a
trailing newline (same output as print1
).
Writes (appends) to
filename the object x in binary format. This format is not human
readable, but contains the exact internal structure of x, and is much
faster to save/load than a string expression, as would be produced by
write
. The binary file format includes a magic number, so that such a
file can be recognized and correctly input by the regular read
or \r
function. If saved objects refer to (polynomial) variables that are not
defined in the new session, they will be displayed in a funny way (see
Section [Label: se:kill]). Installed functions and history objects can not be saved
via this function.
If x is omitted, saves all user variables from the session, together with
their names. Reading such a "named object" back in a gp
session will set
the corresponding user variable to the saved value. E.g after
x = 1; writebin("log")
reading log
into a clean session will set x
to 1.
The relative variables priorities (see Section [Label: se:priority]) of new variables
set in this way remain the same (preset variables retain their former
priority, but are set to the new value). In particular, reading such a
session log into a clean session will restore all variables exactly as they
were in the original one.
Just as a regular input file, a binary file can be compressed
using gzip
, provided the file name has the standard .gz
extension.
In the present implementation, the binary files are architecture dependent
and compatibility with future versions of gp
is not guaranteed. Hence
binary files should not be used for long term storage (also, they are
larger and harder to compress than text files).
The library syntax is void gpwritebin(const char *filename, GEN x = NULL)
.
As write
, in TeX format.