What does it mean in FORTRAN?
DO 11 I = 1,LGTH1
11 ARRAY(I) = 0.D0
DO 12 I = 1,LGTH2
12 IARRAY(I) = 0
In this program 11 and 12 are flags(labels). labels specify the last line of the loop.
So the line
DO 11 I = 1,LGTH1
mean :
Run the line that starts with the flag=11 for LGTH-I rep.
The general form of the do loop is as follows:
do label var = expr1, expr2, expr3
statements
label continue
var is the loop variable (often called the loop index) which must be integer. expr1 specifies the initial value of var, expr2 is the terminating bound, and expr3 is the increment (step).
In cases that statement is a one-line command, we can use this form instead :
do label var = expr1, expr2, expr3
label the-one-line-statement
These are two do loops, in modern Fortran they would look like
DO I = 1,LGTH1
ARRAY(I) = 0.D0
ENDDO
DO I = 1,LGTH2
IARRAY(I) = 0
ENDDO
So, you assign zeros to ARRAY and IARRAY. You could also write this in vector form:
ARRAY(1:LGTH1) = 0.D0
IARRAY(1:LGTH2) = 0
Related
I'm very new to this language and have an assignment to convert some code from Fortran 77 to 90 and fix the code. I'm supposed to do the following:
Remove the implicit statement.
Convert array notation to fixed-shape [meaning IRAN(32) should be IRAN(:)]
Use the size() function to check the array size.
Any help on what to do here would be greatly appreciated. Based on the source code, I think I'm supposed to make a main program, then make subprogram makevec, which uses permutation function px(i); I'm not sure how to do this. Does this sound correct? What about the names of the variables? I looked up some of them (such as iran) and they seem to be related to random number generator modules (but again, I'm not sure of anything in this paragraph). I also found the modules "mod_kinds.F" and "ran_state.F" online but am not sure if they would help the purpose of this program.
I already removed the implicit statement in my program, declared some variables in the main program, and replaced the if loops with "select case (iran(i)." I also got rid of "return" and made everything lowercase.
Here is the source code :
SUBROUTINE MAKEVEC(NVAR,NOFIX,NRANFIX,IRAN,X,VALFIX,RANFIXEST,PX)
IMPLICIT REAL*8(A-H,O-Z)
DIMENSION IRAN(32),X(30),VALFIX(20),PX(32),RANFIXEST(20)
C THIS ROUTINE, CALLED BY MAIN, INPUTS NVAR, NOFIX, NRANFIX, IRAN,
C X, VALFIX, AND RANFIXEST, AND RETURNS PX(I) = A COMBINATION OF THE
C VALUES IN X, VALFIX, AND RANFIXEST, IN THE PROPER ORDER (AS
C DETERMINED BY IRAN).
NNNVAR = 0
NNNFIX = 0
NNNRANFIX = 0
DO I = 1,NVAR+NOFIX+NRANFIX
IF(IRAN(I) .EQ. 1) THEN
NNNVAR = NNNVAR+1
PX(I) = X(NNNVAR)
ENDIF
IF(IRAN(I) .EQ. 0) THEN
NNNFIX = NNNFIX+1
PX(I) = VALFIX(NNNFIX)
ENDIF
IF(IRAN(I) .EQ. 2) THEN
NNNRANFIX = NNNRANFIX+1
PX(I) = RANFIXEST(NNNRANFIX)
ENDIF
END DO
c write (,) "Initialized IG",NNNVAR,NNNFIX,NNNRANFIX
RETURN
END
This is what I have done so far (I know there is a lot of pseudocode and this won't compile):
program Initialized_IG
implicit none
interface
subroutine makevec(var,nofix,nranfix,iran,x,valfix,&
ranfixest,px)
real, intent (in) :: nvar,nofix,nranfix,iran,x,valfix,&
ranfixest
real, intent (out) :: px(i)
REAL(kind=8) :: i
real, dimension(32) :: iran, px
real, dimension(30) :: x
real, dimension(20) :: valfix, ranfixest
integer :: i,nnnvar,nofix,nranfix,sum
sum = nvar + nofix + nranfix
end interface
nnnvar = 0
nnnfix = 0
nnnranfix = 0
CALL RANDOM_NUMBER(i)
call subroutine makevec
select case (iran(i))
case (1)
nnnvar = nnnvar+1
px(i) = x(nnnvar)
case (0)
nnnfix = nnnfix+1
px(i) = valfix(nnnfix)
case (2)
nnnranfix = nnnranfix+1
px(i) = ranfixest(nnnranfix)
end select
write (*,*) "Initialized IG", nnnvar,nnnfix,nnnranfix
end program Initialized_IG
I have a function of some variables, which will yield an array consisted of both negative and positive values (Real). But since only positive values are physically meaningful to me, I want to set all negative values inside the array to be zero.
I have provided my code related to this function below:
The reason I declare a temporary variable 'res' is that I try to build in an IF-ELSE in the position I marked in code as follows:
If (res >= 0) Then
result = res
Else
result = 0
End If
But the error says a scalar-valued expression for S_A if required here.
If instead of res we use res(il,ir) is used,
If (res(il,ir) >= 0) Then
result(il,ir) = res(il,ir)
Else
result = 0
End If
the error says error #6351: The number of subscripts is incorrect.
Is there any way to implement this idea?
Function somefunction(x,y,il,ir) Result(result)
!! ---- begin of declaration ---------------------------
Implicit None
!! boundary indices
Integer, Intent ( in ) :: il,ir
!! the vars
Real ( kind = rk ), Intent ( in ), Dimension ( il:ir ) :: x,y
!! the result
Real ( kind = rk ), Dimension ( il:ir ) :: result
!! temp vars
Real ( kind = rk ), Dimension ( il:ir ) :: res
!! loop index
Integer :: i
!! ---- end of declaration -----------------------------
res = x+y
SA = S_A
!!IF-ELSE!!
End Function somefunction
If you want to have an if statement element wise on an array, you should use the where statement, for example:
program min0
implicit none
real :: res(5, 5), result(5, 5)
call random_number(res)
res=res-0.5
print '(5(F5.2,X))', res
where (res>=0)
result = res
elsewhere
result = 0
end where
print *, '---------------------------------------'
print '(5(F5.2,X))', result
end program min0
I don't know why you get a subscript error, it might help if you tell us which line of the code the error occurs. But of course in the second code, you update a single element of result if res is larger than 0, but set the whole array result to 0 if it isn't. This is almost certainly not what you want.
Cheers
The function appears to take in X and Y dimensioned from (il:if)... say from (3:6), so a vector. However the index later says (il,ir) which means it is a 2 dimensional array.
WHERE seems like a good choice. Another would be a logical MASK to associate the where-positions. It makes sense is PACK and unpack are usd,
Why even say what size the vectors are?
ELEMENTAL Function somefunction(x,y) Result(Res)
!! ---- begin of declaration ---------------------------
Implicit None
Real ( kind = rk ), Intent (IN), Dimension (:) :: x,y
!! the result
Real ( kind = rk ), Dimension ( il:ir ) :: res
!! loop index
Integer :: i
!! ---- end of declaration -----------------------------
res = x+y
WHERE res <= 0
Res = 0
ENDWHERE
!!IF-ELSE!!
End Function somefunction
Then on the calling side... call the function over the range of undecided you want.
Z(1:5) = somefunction(X(1:5),Y(1:5))
So I'm trying to come up with a clever way to make this program read a catalog and take anything falling within specific spatial "grid" boxes and average the data in that box together. I'll paste my horrid attempt below and hopefully you'll see what I'm trying to do. I can't get the program to work correctly (it gets stuck in a loop somewhere that I haven't debugged), and before I bang my head against it anymore I want to know if this looks like a logical set of operations for what I'm looking to do, or if there is a better way to accomplish this.
Edit: To clarify, the argument section is for the trimming parameters---"lmin lmax bmin bmax" set the overall frame, and "deg" sets the square-degree increments.
program redgrid
implicit none
! Variable declarations and settings:
integer :: ncrt, c, i, j, k, count, n, iarg, D, db, cn
real :: dsun, pma, pmd, epma, epmd, ra, dec, degbin
real :: V, Per, Amp, FeH, EBV, Dm, Fi, FeHav, EBVav
real :: lmin, lmax, bmin, bmax, l, b, deg, lbin, bbin
real :: bbinmax, bbinmin, lbinmax, lbinmin
character(len=60) :: infile, outfile, word, name
parameter(D=20000)
dimension :: EBV(D), FeH(D), lbinmax(D), bbinmax(D)
dimension :: bbinmin(D), lbinmin(D)
103 format(1x,i6,4x,f6.2,4x,f6.2,4x,f7.2,3x,f6.2,4x,f5.2,4x,f5.2,4x,f5.2,4x,f6.4)
3 continue
iarg=iargc()
if(iarg.lt.7) then
print*, 'Usage: redgrid infile outfile lmin lmax bmin bmax square_deg'
stop
endif
call getarg(1, infile)
call getarg(2, outfile)
call getarg(3, word)
read(word,*) lmin
call getarg(4, word)
read(word,*) lmax
call getarg(5, word)
read(word,*) bmin
call getarg(6, word)
read(word,*) bmax
call getarg(7, word)
read(word,*) deg
open(unit=1,file=infile,status='old',err=3)
open(unit=2,file=outfile,status='unknown')
write(2,*)"| l center | b center | [Fe/H] avg | E(B-V) avg | "
FeHav = 0.0
EBVav = 0.0
lbinmin(1) = lmin
bbinmin(1) = bmin
degbin = (bmax-bmin)/deg
db = NINT(degbin)
do j = 1, db
bbinmax(j) = bbinmin(j) + deg
lbinmax(j) = lbinmin(j)*cos(bbinmax(j))
print*, lbinmin(j), bbinmin(j), db
cn = 1
7 continue
read(1,*,err=7,end=8) ncrt, ra, dec, l, b,&
V, dsun, FeH(cn), EBV(cn)
if(b.ge.bbinmin(j).and.b.lt.bbinmax(j)) then
if(l.ge.lbinmin(j).and.l.lt.lbinmax(j)) then
FeHav = FeHav + FeH(cn)
EBVav = EBVav + EBV(cn)
cn = cn + 1
end if
end if
goto 7
8 continue
FeHav = FeHav/cn
EBVav = EBVav/cn
write(2,*) lbinmax(j), bbinmax(j), FeHav, EBVav
bbinmin(j+1) = bbinmin(j) + deg
lbinmin(j+1) = lbinmin(j) + deg
end do
close(1)
close(2)
end program redgrid
Below is a small section of the table I'm working with. "l" and "b" are the two coordinates I am working with---they are angular, hence the need to make the grid components "b" and "l*cos(b)." For each 0.5 x 0.5 degree section, I need to have averages of E(B-V) and [Fe/H] within that block. When I write the file all I need are four columns: the two coordinates where the box is located, and the two averages for that box.
| Ncrt | ra | dec | l | b | V | dkpc | [Fe/H] | E(B-V) |
7888 216.53 -43.85 -39.56 15.78 15.68 8.90 -1.19 0.1420
7889 217.49 -43.13 -38.61 16.18 16.15 10.67 -1.15 0.1750
7893 219.16 -43.26 -37.50 15.58 15.38 7.79 -1.40 0.1580
Right now, the program gets stuck somewhere in the loop cycle. I've pasted the terminal output that happens when I run it, along with the command line I'm running it with. Please let me know if I can help clarify. This is a pretty complex problem for a Fortran rookie such as myself---perhaps I'm missing some fundamental knowledge that would make it much easier. Anyways, thanks in advance.
./redgrid table2.above redtest.trim -40 0 15 30 0.5
-40.0000000 15.0000000 30 0.00000000 0.00000000
-39.5000000 15.5000000 30 -1.18592596 0.353437036
^it gets stuck after two lines.
I assume that the program does what you want it to do, but you are looking for a few things to tidy the code up.
Well first up, I'd fix up the indentation.
Secondly, I'd not use unit numbers below 10.
INTEGER, PARAMETER :: in_unit = 100
INTEGER, PARAMETER :: out_unit = 101
...
OPEN(unit=in_unit, file=infile, status='OLD")
...
READ(in_unit, *) ...
...
CLOSE(in_unit)
Thirdly, I'd not use GOTOs and labels. You can do that in a loop far easier:
INTEGER :: read_status
DO j = 1, db
...
read_loop : DO
READ(in_unit, *, IOSTAT=read_status) ...
IF (read_status == -1) THEN ! EOF
EXIT read_loop
ELSEIF (read_status /= 0) THEN
CYCLE read_loop
ENDIF
...
END DO read_loop
...
END DO
There are a few dangers in your code, and even in this one above: It can lead to infinite loops. For example, if the opening of infile fails (e.g. the file doesn't exist), it loops back to label 3, but nothing changes, so it will eventually again try to open the same file, and probably have the same error.
Same above: If READ repeatedly fails without advancing, and without the error being an EOF, then the read loop will not terminate.
You have to think about what you want your program to do when something like this happens, and code it in. (For example: Print an error message and STOP if it can't open the file.)
You have a very long FORMAT statement. You can leave it like that, though I'd probably try to shorten it a bit:
103 FORMAT(I7, 2F10.2, F11.2, 4F9.2, F10.4)
This should be the same line, as numbers are usually right-aligned. You can also use strings as a format, so you could also do something like this:
CHARACTER(LEN=*), PARAMETER :: data_out_form = &
'(I7, 2F10.2, F11.2, 4F9.2, F10.4)'
WRITE(*, data_out_form) var1, var2, var3, ...
and again, that's one less label.
The code consists of a do-loop and creates arrays of data as long as running. I need these arrays added to a file as new columns.
The first column is fixed (wavelengths) and the second is generated within the first run:
OPEN (unit=11,file=filename // '.csv')
WRITE(11,'(i4,A1,f10.6)') (lambda(ii),tab,resv(ii), ii=1,nw)
CLOSE(11)
lambda are the wavelengths (4 digits), tab is declared as char(9) and resv are my data (floating). The array consists of nw=2000 items.
First time running the script gives me a nice output which I can load into MS Excel as .csv
However, the script is to return to the beginning of the loop, calculate new data and store the changed "resv" items into a new column.
But when I go like
WRITE(11,'(T17,i4,A1,f10.6)') (lambda(ii),tab,resv(ii), ii=1,nw)
the new data is indeed stored into column 17, but all the data before is being removed!
So how can I tell Fortran to "add" a new column?
Try a variant of this. Have a look at the code in addcolumn. The restriction is that your line can't be more than 1024 characters long. You can increase the size of the array to suit your needs.
module mod_helper
integer, parameter:: AMAX = 10
integer, dimension(AMAX):: coldata
integer:: revision
contains
subroutine init
revision = 0
do ii = 1, AMAX
coldata(ii) = ii
end do
end subroutine init
subroutine increment(howmuch)
integer, intent(in):: howmuch
coldata = coldata + howmuch
end subroutine
subroutine addcolumn(csvname)
character*(*), intent(in) csvname
integer(kind=2):: status
integer:: prevlen
character(1024):: prev, oldname, newname
integer, parameter:: oldfile = 20, newfile = 30
write(oldname, "(A,I3.3,'.csv')") csvname, revision
revision = revision + 1
write(newname, "(A,I3.3,'.csv')") csvname, revision
if (revision .gt. 1) then
! Open the old file
open(oldfile, file=oldname, access="sequential", status="old")
end if
open(newfile, file=newname, access="sequential", status="new", action="write")
prev = ' '
do ii = 1, AMAX
if (revision .gt. 1) then
! read previous contents as a string
read(oldfile, "(A)") prev
prevlen = len(trim(prev))
else
prevlen = 1
end if
! write previous and new contents
write(newfile, "(A, I4, ',')") prev(1:prevlen), coldata(ii)
end do
! delete the previous file
if (revision .gt. 1) close(oldfile, status='delete')
close(newfile)
end subroutine
end module
program main
use mod_helper
call init
call addcolumn('col')
call increment(1)
call addcolumn('col')
call increment(20)
call addcolumn('col')
end program
I have this SML code. I don't know why I cannot compile this :
fun score =
let
val sum = 3; (* error at this line : SYNTAX ERROR : inserting LPAREN *)
if sum div 2 > 0
then sum = 0
else sum = 1
(*some other code*)
in
sum (* I want to return sum after some steps of calculation *)
end
There are more issues with your code, than jacobm points out.
You are also missing a function argument. Functions in SML always takes one argument. For example
fun score () =
let val sum = 3
val sum = if sum div 2 > 0
then sum = 0
else sum = 1
in
sum
end
However this still doesn't make much sense. since the expressions sum = 0 and sum = 1 evaluates to a Boolean.
A let-expression is used to make some local declarations which are only visible inside the in ... end part. Thus the calculations you wan't to do with sum, should probably be done inside the in ... end part, unless you wan't to express it as a means of a function.
One such example is
fun score () =
let val sum = 3
in
if sum div 2 > 0
then ...
else ...
end
If we look at the syntax of a let-expression, it probably makes more sense
let
<declaration>
in
<expr> ; ... ; <expr>
end
Since if-then-else is an expression, it can't be in the "declarations part" by itself.
That syntax just isn't legal -- in between let and in all you're allowed to have is a series of val name = expr fragments. You can do this, though:
fun score =
let val sum = 3
val sum = if sum div 2 > 0
then sum = 0
else sum = 1
in
sum
end
I would consider it a bit of a weird style to use sum for both variable names, but it's legal.