Fortran does'nt end when obtain unexpected value? - formatting

I've got a program, which compute a several variables and then these variables are writing in to the output file.
Is it possilbe, that when my program can't get a correct results for my formula, it does'nt terminate?
To clarify what I do, here is part of my code, where the variable of my interest are compute:
dx=x(1,i)-x(nk,i)
dy=y(1,i)-y(nk,i)
dz=z(1,i)-z(nk,i)
call PBC(dx,dy,dz)
r2i=dx*dx+dy*dy+dz*dz
r2=r2+r2i
r2g0=0.0d0
r2gx=0.0d0
dx=x(1,i)-x(2,i)
call PBC(dx,dy,dz)
rspani=dsqrt(dx*dx)
do ii=1,nk-1
rx=x(ii,i)
ry=y(ii,i)
rz=z(ii,i)
do jj=ii+1,nk
dx=x(jj,i)-rx
dy=y(jj,i)-ry
dz=z(jj,i)-rz
call PBC(dx,dy,dz)
r21=dx*dx+dy*dy+dz*dz
r21x=dx*dx
r2g=r2g+r21
r2gx=r2gx+r21x
r2g0=r2g0+r21
rh=rh+1.0d0/dsqrt(r21)
rh1=rh1+1.0d0
ir21=dnint(dsqrt(r21)/dr)
p(ir21)=p(ir21)+2.0D0
dxs=dsqrt(r21x)
if(dxs.gt.rspani) rspani=dxs
end do
and then in to the output I just write these variables:
write(12,870)r2i,sqrt(r2i),r2g0,r2gx/(nk*nk)
870 FORMAT(3(f15.7,3x),f15.7)
The x, y, z are actully generate via a random number generator.
The problem is that my output contains, correct values for lets say 457 lines, and then a one line is just "*********" when I use mc viewer and then the output continues with correct values, but let's say 12 steps form do cycle which compute these variables is missing.
So my questions are basic:
Is it possible, that my program can't get a correct numbers, and that's why the result is not writing in to the program?
or
Could it this been caused due to wrong output formating or something related with formating?
Thank you for any suggestion

********* is almost certainly the result of trying to write a number too large for the field specified in a format string.
For example, a field specified as f15.7 will take 1 spot for the decimal point, 1 spot for a leading sign (- will always be printed if required, + may be printed if options are set), 7 for the fractional digits, leaving 6 digits for the whole part of the number. There may therefore be cases where the program won't fit the number into the field and will print 15 *s instead.
Programs compiled with an up to date Fortran compiler will write a string such as NaN or -Inf if they encounter a floating-point number which represents one of the IEEE special values

Related

Remove decimal separator with output format on real values in Fortran [duplicate]

So I have some code that does essentially this:
REAL, DIMENSION(31) :: month_data
INTEGER :: no_days
no_days = get_no_days()
month_data = [fill array with some values]
WRITE(1000,*) (month_data(d), d=1,no_days)
So I have an array with values for each month, in a loop I fill the array with a certain number of values based on how many days there are in that month, then write out the results into a file.
It took me quite some time to wrap my head around the whole 'write out an array in one go' aspect of WRITE, but this seems to work.
However this way, it writes out the numbers in the array like this (example for January, so 31 values):
0.00000 10.0000 20.0000 30.0000 40.0000 50.0000 60.0000
70.0000 80.0000 90.0000 100.000 110.000 120.000 130.000
140.000 150.000 160.000 170.000 180.000 190.000 200.000
210.000 220.000 230.000 240.000 250.000 260.000 270.000
280.000 290.000 300.000
So it prefixes a lot of spaces (presumably to make columns line up even when there are larger values in the array), and it wraps lines to make it not exceed a certain width (I think 128 chars? not sure).
I don't really mind the extra spaces (although they inflate my file sizes considerably, so it would be nice to fix that too...) but the breaking-up-lines screws up my other tooling. I've tried reading several Fortran manuals, but while some of the mention 'output formatting', I have yet to find one that mentions newlines or columns.
So, how do I control how arrays are written out when using the syntax above in Fortran?
(also, while we're at it, how do I control the nr of decimal digits? I know these are all integer values so I'd like to leave out any decimals all together, but I can't change the data type to INTEGER in my code because of reasons).
You probably want something similar to
WRITE(1000,'(31(F6.0,1X))') (month_data(d), d=1,no_days)
Explanation:
The use of * as the format specification is called list directed I/O: it is easy to code, but you are giving away all control over the format to the processor. In order to control the format you need to provide explicit formatting, via a label to a FORMAT statement or via a character variable.
Use the F edit descriptor for real variables in decimal form. Their syntax is Fw.d, where w is the width of the field and d is the number of decimal places, including the decimal sign. F6.0 therefore means a field of 6 characters of width with no decimal places.
Spaces can be added with the X control edit descriptor.
Repetitions of edit descriptors can be indicated with the number of repetitions before a symbol.
Groups can be created with (...), and they can be repeated if preceded by a number of repetitions.
No more items are printed beyond the last provided variable, even if the format specifies how to print more items than the ones actually provided - so you can ask for 31 repetitions even if for some months you will only print data for 30 or 28 days.
Besides,
New lines could be added with the / control edit descriptor; e.g., if you wanted to print the data with 10 values per row, you could do
WRITE(1000,'(4(10(F6.0,:,1X),/))') (month_data(d), d=1,no_days)
Note the : control edit descriptor in this second example: it indicates that, if there are no more items to print, nothing else should be printed - not even spaces corresponding to control edit descriptors such as X or /. While it could have been used in the previous example, it is more relevant here, in order to ensure that, if no_days is a multiple of 10, there isn't an empty line after the 3 rows of data.
If you want to completely remove the decimal symbol, you would need to rather print the nearest integers using the nint intrinsic and the Iw (integer) descriptor:
WRITE(1000,'(31(I6,1X))') (nint(month_data(d)), d=1,no_days)

How would I create a function in objective-c that would correctly output the results of in mathematical precedence?

I want to create a mathematical calculator in objective-C. I need it to run
through a command line. The user will enter an equation like 4 + 2 * 12 etc. The output should calculate the 2 and 12 first because they are times by. How would I create a command line program that creates output based on mathematical order or precedence. for example solving whats in the brackets first then anything that is multiplied and or divided by etc etc.
there are multiple programs available online for this here is just one http://www.wikihow.com/Make-a-Command-Prompt-Calculator, in the CMD line you can specify precedence by simply using parenthesis like the following C:> set /a ((2*12)+4) obviously replacing hard coded values with that passed to a variable.

Fortran runtime error: Bad integer for item 0 in list input?

How do I fix the Fortran runtime error: Bad integer for item 0 in list input?
Below is the Fortran program which generates a runtime error.
CHARACTER CNFILE*(*)
REAL BOX
INTEGER CNUNIT
PARAMETER ( CNUNIT = 10 )
INTEGER NN
OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'OLD' )
READ ( CNUNIT,* ) NN, BOX
The error message received from gdb is :
At line 688 of file MCNPT.f (unit = 10, file = 'LATTICE-256.txt')
Fortran runtime error: Bad integer for item 0 in list input
[Inferior 1 (process 3052) exited with code 02]
(gdb)
I am not sure what options must be specified for READ() to read to numbers from the text file. Does it matter if the two numbers on the same line are specified as either an integer or a real in the text file?
Below is the gdb execution of the program using a break point at the open call
Breakpoint 1, readcn (
cnfile=<error reading variable: Cannot access memory at address 0x7fffffffdff0>,
box=-3.37898272e+33, _cnfile=30) at MCNPT.f:686
Since you did not specify form="unformatted" on the open statement, the unit / file is opened for formatted IO. This is appropriate for a human-readable text file. ("unformatted" would be used for a non-human readable file in computer-native format, sometimes called "binary".) Therefore you should provide a format on the read, or use list-directed read, i.e., read(unit, *). To advise on a particular format we would have to know the layout of the numbers in the file. A possible read with format is: read (CNUINT, '(I4, 2X, F6.2)' ) NN, BOX
P.S. I'm answering the question in your question and not the title, which seems unrelated.
EDIT: now that you are show the text data file, a list-directed read looks easier. That is because the data doesn't line up in columns. It seems that the file has two integers on the first line, then three real numbers on each of the following lines. Most likely you need a different read for the first line. Is the code sample that you are showing us trying to read the first line, or one of the later lines? If the first line, it would seem plausible to read into two integer variables. If a later line, into two or three real variables. Two if you wish to skip the third data item on the line.
EDIT 2: the question has been substantially altered several times, which is very confusing. The first line of the text file that was shown in one version of the question contained integers, with later lines having reals. Since the listed-directed read is reading into an integer and a floating variable, it will have problems if you attempt to use it on the later lines that have two real values.

'Bad repeat count' while inputting a file, FORTRAN

I am trying to read a file into my code.
there are 2 subroutines, one which writes a file and the other which reads it.
the writing part was:
write(*,*)'entered refile, shall make file'
ileunitA=int(presentstep)
write(fname,1012)ileunitA
1012 format('DATA_',i6.6,'.dat')
write(fnam,1112)index
1112 format('pp',i3.3)
open(UNIT=ileunitA,FILE=fname)
!variables from module global
write(ileunita,*)u,v,w,pc,p,p0,rho1,gam,con
write(ileunita,*)aip,aim,ajp,ajm,akp,akm,ap,ap0
write(ileunita,*) scon,smomu,smomv,smomw
...
The reading part was as follows(in another subroutine):
ileunita=25;
open(unit=ILEUNITA,file='DATA_010500.dat')
!variables from module global
read(ileunita,*)u,v,w,pc,p,p0,rho1,gam,con
read(ileunita,*)aip,aim,ajp,ajm,akp,akm,ap,ap0
read(ileunita,*) scon,smomu,smomv,smomw
...
When I run the code, it shows the following error:
At line 3682 of file bub2.f90 (unit = 25, file = 'DATA_000001.dat')
Fortran runtime error: Bad repeat count in item 1 of list input
Can anyone help me figure out what could be the problem? And what is 'repeat count'. What is a 'bad' repeat count? Thanks
Guessing a little (you could show the text in the problematic line in your question...), but you are using list directed input (and output) with the * as the second specifier in the read (and write) statements. List directed input allows multiple fields that have the same value to be represented using the syntax r*c, where r is a numeric repeat count and c is the value to be repeated.
If any of your output items generate a field that contains a * then that could be confusing the processing of input.
(It is permissible (though rare) for a processor to represent multiple output fields that have the same value using a repeat count, for example WRITE (unit,*) 23, 23, 23, 23 could result in an input file that contains the text 4*23.)
List directed input also has some other features, such as the handling of delimiter characters, the / character causing input processing to terminate and the possibility and handling of null values. Some of these features may surprise those not familiar with the rules (which are inspired by typical short cuts taken when input was submitted via punched cards), which why it is often better to avoid list directed input and output and use an explicit format instead.
If any of your data fields are of type character you should consider using a non-default DELIM mode to avoid any special characters within the character variable value from confusing the input processing.

Fortran 90: How to correctly read an integer among other real

I have created a Fortran 90 code to filter and convert the text output of another program in a csv form. The file contains a table with columns of various types (character, real, integer). There is a column that generally contains decimal values (probability values). BUΤ, in some rows, where the value should be decimal "1.000", the value is actually integer "1".
I use "F5.3" specifier to read this column and I have the same format statement for every row of the table. So, when the code finds "1", it reads ".001", because it does not find a decimal point.
What ways could I use to correctly (and generally) read integers among other decimals?
Could I specify "unformatted" input only for a number of "spaces"?
The data edit descriptor fw.d for floating point format specification is for input normally used with zero d (it cannot be ommited). Nonzero d is used in the rare case when the floating point data is stored as scaled integers, or you do some unit conversion from the integer values.
You could try using list-directed input: use a * instead of a format specifier. This would be for the entire read, not selected items. Or you could read the lines into a string test their contents to decide how to read them. If the sub-string has a decimal point: read (string(M:N), '(F5.3)') value. If it doesn't, use a different format, e.g., perhaps read as as F5.0.
P.S. "unformatted" is reading binary data without conversion ... it is a direct copy of the data from the file to the data item. "listed-directed" is the Fortran term for reading & converting data without using a format specification.
well here's someting new to me: f90 allows a mix of comma and space delimiters for a simple list directed read:
read(unit,*)v1,v2,v3,v4
with input
1.222 2 , 3.14 , 4
yields
1.222000 2.000000 3.140000 4.000000