Files
calc/help/mod
Landon Curt Noll cf419fb329 Added several conversion funcions, plus minor updates
Added several conversion functions:

    Added builtin functions to convert between degrees and
    degrees, minutes and seconds under the config("mod")
    round rules:

	d2dms(degs, d, m, s [,rnd]) - given degs, compute d, m, s
	d2dm(degs, d, m [,rnd]) - given degs, compute d, m

	See help/d2dms and help/d2dm.

    Example:

	; print d2dms(360.321,deg=,min=,sec=), deg, min, sec;
	0.321 0 19 15.6

	; print d2dm(360.321,deg=,min=), deg, min;
	0.321 0 19.26

    Added builtin functions to convert between gradians and
    gradians, minutes and seconds under the config("mod")
    round rules:

	g2gms(grads, g, m, s [,rnd]) - given grads, compute g, m, s
	g2gm(grads, g, m [,rnd]) - given grads, compute g, m

	See help/g2gms and help/g2gm.

    Example:

	; print g2gms(400.321,grad=,min=,sec=), grad, min, sec;
	0.321 0 19 15.6

	; print g2gm(400.321,grad=,min=), grad, min;
	0.321 0 19.26

    Added builtin functions to convert between hours and
    hours, minutes and seconds under the config("mod")
    round rules:

	h2hms(hours, h, m, s [,rnd]) - given hours, compute h, m, s
	h2hm(hours, h, m [,rnd]) - given hours, compute h, m

	See help/h2hms and help/h2hm.

    Example:

	; print h2hms(24.321,hour=,min=,sec=), hour, min, sec;
	0.321 0 19 15.6

	; print h2hm(24.321,hour=,min=), hour, min;
	0.321 0 19.26

In addtion:

    Renumbered regression tests 3408 thru 3437, to 9102 thru 9131.

    Updated Added hms.cal resource file to use h2hms() builtin.
    Updated Added dms.cal resource file to use d2dms() builtin.

    Fix minor typo in help/mod SYNOPSIS.
    Fix minor typo in help/quo SYNOPSIS.

    Added a few more examples to help/strcmp.
2021-09-26 04:38:09 -07:00

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NAME
mod - compute the remainder for an integer quotient
SYNOPSIS
mod(x, y [,rnd])
x % y
TYPES
If x is a matrix or list, the returned value is a matrix or list v of
the same structure for which each element v[[i]] = mod(x[[i]], y, rnd).
If x is an xx-object or x is not an object and y is an xx-object,
this function calls the user-defined function xx_mod(x, y, rnd);
the types of arguments and returned value are as required by the
definition of xx_mod().
If neither x nor y is an object, or x is not a matrix or list:
x number (real or complex)
y real
rnd integer, defaults to config("mod")
return number
DESCRIPTION
The expression:
x % y
is equivalent to call:
mod(x, y)
The function:
mod(x, y, rnd)
is equivalent to:
config("mod", rnd), x % y
except that the global config("mod") value does not change.
If x is real or complex and y is zero, mod(x, y, rnd) returns x.
If x is complex, mod(x, y, rnd) returns
mod(re(x), y, rnd) + mod(im(x), y, rnd) * 1i.
In the following it is assumed x is real and y is nonzero.
If x/y is an integer mod(x, y, rnd) returns zero.
If x/y is not an integer, mod(x, y, rnd) returns one of the two
values of r for which for some integer q exists such that x = q * y + r
and abs(r) < abs(y). Which of the two values or r that is returned is
controlled by rnd.
If bit 4 of rnd is set (e.g. if 16 <= rnd < 32) abs(r) <= abs(y)/2;
this uniquely determines r if abs(r) < abs(y)/2. If bit 4 of rnd is
set and abs(r) = abs(y)/2, or if bit 4 of r is not set, the result for
r depends on rnd as in the following table:
rnd & 15 sign of r parity of q
0 sgn(y)
1 -sgn(y)
2 sgn(x)
3 -sgn(x)
4 +
5 -
6 sgn(x/y)
7 -sgn(x/y)
8 even
9 odd
10 even if x/y > 0, otherwise odd
11 odd if x/y > 0, otherwise even
12 even if y > 0, otherwise odd
13 odd if y > 0, otherwise even
14 even if x > 0, otherwise odd
15 odd if x > 0, otherwise even
NOTE: Blank entries in the table above indicate that the
description would be complicated and probably not of
much interest.
The C language method of modulus and integer division is:
config("quomod", 2)
config("quo", 2)
config("mod", 2)
This dependence on rnd is consistent with quo(x, y, rnd) and
appr(x, y, rnd) in that for any real x and y and any integer rnd,
x = y * quo(x, y, rnd) + mod(x, y, rnd).
mod(x, y, rnd) = x - appr(x, y, rnd)
If y and rnd are fixed and mod(x, y, rnd) is to be considered as
a canonical residue of x % y, bits 1 and 3 of rnd should be
zero: if 0 <= rnd < 32, it is only for rnd = 0, 1, 4, 5, 16, 17,
20, or 21, that the set of possible values for mod(x, y, rnd)
form an interval of length y, and for any x1, x2,
mod(x1, y, rnd) = mod(x2, y, rnd)
is equivalent to:
x1 is congruent to x2 modulo y.
This is particularly relevant when working with the ring of
integers modulo an integer y.
EXAMPLE
; print mod(11,5,0), mod(11,5,1), mod(-11,5,2), mod(-11,-5,3)
1 -4 -1 4
; print mod(12.5,5,16), mod(12.5,5,17), mod(12.5,5,24), mod(-7.5,-5,24)
2.5 -2.5 2.5 2.5
; A = list(11,13,17,23,29)
; print mod(A,10,0)
list (5 elements, 5 nonzero):
[[0]] = 1
[[1]] = 3
[[2]] = 7
[[3]] = 3
[[4]] = 9
LIMITS
none
LINK LIBRARY
void modvalue(VALUE *x, VALUE *y, VALUE *rnd, VALUE *result)
NUMBER *qmod(NUMBER *y, NUMBER *y, long rnd)
SEE ALSO
quo, quomod, //, %
## Copyright (C) 1999-2006 Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL. You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
##
## Under source code control: 1995/09/18 02:09:31
## File existed as early as: 1995
##
## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/