smr@beta.lanl.gov (Shawn) (07/22/89)
Read the statement: IF(MOD(N,2).EQ.0)THEN I'm new at the language and was looking over a program written as an example and became quite confused when I read MOD what does it signify in this statement there is no other reference to MOD... Anyone who might be able to tell me would be appreciated. thanks.
cdb@hpclcdb.HP.COM (Carl Burch) (07/31/89)
> IF(MOD(N,2).EQ.0)THEN > I'm new at the language and was looking over a program written as an > example and became quite confused when I read MOD what does it signify > in this statement there is no other reference to MOD... Short answer : This is FORTRAN 77 for (in Pascal) : IF odd(N) THEN Longer answer : MOD is the modulus (like remainder if all arguments are positive) function. It is an intrinsic function in FORTRAN 77, so no other references are necessary. The remainder of any even positive number divided by two is zero. I hedge by restricting the above to the positive case because what happens when either argument is negative is the subject of many theological arguments I do not desire to join. Carl Burch HP Data and Languages Division
BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) (07/31/89)
mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the
cell in matrix Mod with the coordinates of n,2(like geographical coordinates).
MOD 1 2 3 4 5
2
3
.
.
n X < mod(n,2) reffers to this cell
good luck
Fight the Fort ran
Dannychidsey@smoke.BRL.MIL (Irving Chidsey ) (07/31/89)
In article <588BLUMBERG@BGUVM> BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) writes:
<mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the
<cell in matrix Mod with the coordinates of n,2(like geographical coordinates).
<MOD 1 2 3 4 5
< 2
< 3
< .
< .
< n X < mod(n,2) reffers to this cell
< good luck
< Fight the Fort ran
< Danny
Sorry, but mod( n, 2 ) is almost certainly Fortran for N modulo 2, which is
mathematics for n/2 with no fractional part.
I don't thinkit is standard fortran, but it is common fortran.
Irv
--
I do not have signature authority. I am not authorized to sign anything.
I am not authorized to commit the BRL, the DOA, the DOD, or the US Government
to anything, not even by implication.
Irving L. Chidsey <chidsey@brl.mil>riley@batcomputer.tn.cornell.edu (Daniel S. Riley) (07/31/89)
In article <10632@smoke.BRL.MIL> chidsey@brl.arpa (Irving Chidsey (INF) <chidsey>) writes: >In article <588BLUMBERG@BGUVM> BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) writes: ><mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the ><cell in matrix Mod with the coordinates of n,2(like geographical coordinates). >Sorry, but mod( n, 2 ) is almost certainly Fortran for N modulo 2, which is >mathematics for n/2 with no fractional part. > >I don't thinkit is standard fortran, but it is common fortran. Ok, enough of this. mod() is the remainder function. mod(n, 2) returns the remainder when n is divided by 2--this is the usual way to check for even or odd (or test the least significant bit, same thing). It is a standard FORTRAN-77 intrinsic. The definition is something like mod(n, m) = n - m*int(n/m) mod() is really misnamed, since it returns the remainder, not the modulo. (For those who care--the remainder takes the sign of the first argument, the modulo takes the sign of the second. mod(x, 2*pi) ought to return a number between 0 and 2*pi, but in FORTRAN-77 it returns a number between -2*pi and 2*pi, depending on the sign of x.) As far as I know, you could declare an array named mod(), but this is generally considered to be bad (and confusing) programming practice. -Dan Riley (riley@tcgould.tn.cornell.edu, cornell!batcomputer!riley) -Wilson Lab, Cornell U.
silvert@cs.dal.ca (Bill Silvert) (07/31/89)
In article <588BLUMBERG@BGUVM> BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) writes: >mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the >cell in matrix Mod with the coordinates of n,2(like geographical coordinates). MOD(I, J) is the remainder when I is divided by J, like I % J in C. It is defined at the top of p. 15-23 of the standard, and is technically defined as I - INT(I/J)*J, which unfortunately is not an optimal choice for negative numbers. One of the advantages of having a standard is that questions can be correctly answered on the basis of facat. Dan, are you listening? -- Bill Silvert, Habitat Ecology Division. Bedford Institute of Oceanography, Dartmouth, NS, Canada B2Y 4A2 UUCP: ...!{uunet,watmath}!dalcs!biomel!bill Internet: biomel@cs.dal.CA BITNET: bs%dalcs@dalac.BITNET
johnl@esegue.uucp (John Levine) (07/31/89)
In article <10632@smoke.BRL.MIL> chidsey@brl.arpa (Irving Chidsey (INF) <chidsey>) writes: >In article <588BLUMBERG@BGUVM> BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) writes: ><mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the... >Sorry, but mod( n, 2 ) is almost certainly Fortran for N modulo 2, which is >mathematics for n/2 with no fractional part. >I don't thinkit is standard fortran, but it is common fortran. Oh, for heavens' sakes. MOD is the intrisic integer remainder function and has been since about 1957 (when it was sometimes called MODF.) I have never seen a version of Fortran that doesn't have it, including the original Fortran I. If you have a simple question like this, it would be a kindness to the 200,000 people on the net if you spent a few minutes looking it up, rather than blatting it all over the world. (Not having a manual is no excuse -- it's certainly quicker to go out and find one than wait for the net to answer.) Grouchily, -- John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869 {ima|lotus}!esegue!johnl, johnl@ima.isc.com, Levine@YALE.something Massachusetts has 64 licensed drivers who are over 100 years old. -The Globe
sdry@vax5.CIT.CORNELL.EDU (07/31/89)
In article <588BLUMBERG@BGUVM> BLUMBERG@BGUVM.BITNET (Dan Blumberg, Dept. Of Geog. Ben Gurion Univ. Israel) writes: >mod is the name of a two fimensional matrix sized I by J. MOd (n,2) is the >cell in matrix Mod with the coordinates of n,2(like geographical coordinates). >MOD 1 2 3 4 5 > 2 > 3 > . > . > n X < mod(n,2) reffers to this cell > good luck > Fight the Fort ran > Danny CDIR$ FLAME(MILD) ! Not a new CFT directive (in case you wondered) This is only true if the program unit contains a DIMENSION or equivalent declarative statement defining array MOD. Normally, MOD is an intrinsic function ( MOD(I,J) returns the remainder of the division of I by J; thus, IF (MOD(N,2).EQ.0) tests whether N is even. The original posting had just such a statement.) As a general rule, an identifier followed by an argument list within parentheses is interpreted as an external (or intrinsic) function call unless it has been explicitly declared as an array. CDIR$ FLAME(OFF) Sergio Gelato
jmlake@uicsrd.csrd.uiuc.edu (08/03/89)
MOD is the integer modulus function. MOD(N, 2).eq.0 is testing to see whether N is EVEN. It is not a two-dimensional array, as a previous message indicated. J. Michael Lake Center for Supercomputer Research & Development Graduate Research Assistant 305 Talbot Laboratory 104 South Wright St. University of Illinois Urbana IL 61821 (217) 333-4168 jmlake@uiuc.edu uxc.cso.uiuc.edu!uicsrd.csrd.uiuc.edu!jmlake