This should be quite simple, but I can't manage to read in a floating point number in Fortran. My program test.f looks like this:
PROGRAM TEST
open(UNIT=1,FILE='test.inp')
read(1,'(f3.0)')line
STOP
END
The input file test.inp simply contains a single float: 1.2
Now the compiling of my testfile goes fine, but when I run it I get an error:
At line 4 of file test.f (unit = 1, file = 'test.inp')
Fortran runtime error: Expected REAL for item 1 in formatted transfer, got INTEGER
(f3.0)
^
I've tried different modifications of the code and also googling for the error message, but with no result. Any help would be greatly appreciated!
Regards,
Frank
Your variable line is implicitly defined as integer. This doesn't work with thef edit descriptor. If you want to read an integer use i edit descriptor (i3 for example). Otherwise declare line as real to math the "f" descriptor.
Note beside: the .0 is not a problem, because if Fortran gets a number with decimal point the .0 part in the descriptor is ignored. It is only used when an number without a decimal is entered and then it uses the number behind the decimal point in the desciptor to add a decimal point into the right place. For with F8.5, 123456789 is read as 123.45678. More ont this here http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/fortran/lin/compiler_f/lref_for/source_files/pghredf.htm .
In your read statement
read(1,'(f3.0)')line
the f3.0 tells tour program to read 3 digits with 0 digits after the decimal (this is what the n.m syntax means). So I presume that the program is just reading 1 from the file (not 1.2), which is an integer. Try replacing that line with something like
read(1,'(f3.1)')line
although, if the number in your file is likely to change and be larger than 9.9 or have more than one decimal place you should increase the field width to something larger than 3.
See the documentation of the read intrinsic and for data edit descriptors for more information on reading and writing in Fortran.
Edit: the format specifier, the second argument in quotes in your read statment, has the form fw.d, where f indicates that the data to read is a floating point number, w is the width of the field including all blanks and decimal points and d specifies the number of digits to the right of the decimal point.
I would suggest reading/writing list formatted data, unless you have a very strong reason to do otherwise. assuming that you're reading in from a file with just a single float or integer in a single line, like this
123.45
11
42
then this should do the reading
real*8 :: x,y,z
open(1,file=filename)
read(1,*)x
read(1,*)y
read(1,*)z
close(1)
Related
I'm learning Fortran and found some strange things when writing with a format (I'm using Fortran onlinegdb)
Program Hello
real, dimension(3,2):: array
array = 0
write(*, '(A,/, A,/, F5.2, F5.2)') &
"1","2",((array(i, j), i = 1,3), j = 1,2)
End Program Hello
I expected
1
2
0.00 0.00
0.00 0.00
0.00 0.00
I get
1
2
0.00 0.00
0.00 0.00
What's wrong?
Vladimir F is correct in saying that the format given does not suit the items that are provided for output: with format reversion after writing two real values, the control goes back to looking at the edit descriptor A but what corresponds to that isn't another character variable. This is not allowed.
However, the format suggested in an earlier revision of that other answer also does not give the output that you expect. If you want to write pairs of numbers on each line relying on an unlimited repeat specification, you'll need to explicitly put the file positioning into the format:
write(*, '(2(A,/),*(2F5.2,:,/))') "1", "2", transpose(array)
Without the / edit in there at the end, the repeat will mean that all elements of the array go in the same record. We also have : there, so that we don't get an extra line break after the final array element.
(I've also transposed the output array, as that's probably what you really mean. The implied do loop in the original output is a little unexpected and makes more sense moving over the final index first.)
With a limited repeat specification, as shown in the corrected form of that answer, format reversion does imply positioning:
write(*, '(2(A,/), 2(F5.2))') "1","2", transpose(array)
After processing the 2(F5.2) reversion has this reused while there are still elements to write out.
In summary, if you are relying on format reversion to "skip" earlier parts of a format while keeping new records, you must correctly mark the part of the whole format to revert to using parentheses. With just the whole format surrounded by parentheses, and no others, format reversion reuses the whole format.
You requested two strings to be printed, each on a new line, then two floating point numbers. That happened correctly.
But then there were still remaining items in the array. The format interpretation started again from the beginning with a new line and again for two strings and two numbers. But the array did not contain any strings...
Try '(A,/, A,/, (F5.2, F5.2))' instead. That will repeat the two-times floating point number format group until there are still numbers to be processed but this time the format does not return to the very beginning. (Note: the old and untested revision of the answer featured an extra repeat count - I did not realize this will disable the format reversion.)
I got a Fortran code for K-means clustering from online.
As I am new to Fortran, I do not have an idea about the required input file format for the code as below.
How to prepare an input file according to this Fortran code?
infile1='D1_TR_all_cent63.dat'
OPEN(1,FILE=infile1,form='formatted',access='direct',
+ recl=429)
istep=nvectors/nclusters
DO i=1,nclusters
READ(1,23,rec=istep*(i-1)+1)(vec(j),j=1,42)
DO k=1,nelements
centroid(i,k)=vec(k)
END DO
END DO
23 format(42(f10.3))
It's looking for a file where each line contains 42 fields where it expects to find fixed point numbers. That's the 42(f10.3) in the format
statement. Each of those fields is 10 characters wide; there are no commas or other separator characters between them, although spaces are allowed.
For example:
123456.789 123.123 -123.123 12345.678 0.000
(and onward until there are 42 of those).
Most FORTRAN implementations will be a bit merciful on reading: You can leave off some of the after-decimal point digits, or have a space after the number (but you have to stay in the 10-character fields). But not all do, so it might be better to prepare your input with 6 digits (including sign, if needed, and allowing spaces instead) before the decimal point and three after.
I am trying to create an MDM file using HLM 7 Student version, but since I don't have access to SPSS I am trying to import my data using ASCII input. As part of this process I am required to input the data format Fortran style. Try as I might I have not been able to understand this step. Could someone familiar with Fortran (or even better HLM itself) explain to me how this works? Here is my current understanding
From the example EG3.DAT they give
(A4,1X,3F7.1)
I think
A4 signifies that the ID is 4 characters long.
1X means skip a space.
F.1 means that it should read 1 decimal places.
I am very confused about what 3F7 might mean.
EG3.DAT
2020 380.0 40.3 12.5
2040 502.0 83.1 18.6
2180 777.0 96.6 44.4
Below are examples from the help documents.
Rules for format statement
Format statement example
EG1 data format
EG2 data format
EG3 data format
One similar question is Explaining Fortran Write Format. Unfortunately it does not explicitly treat the F descriptor.
3F7.1 means 3 floating point numbers, each printed over 7 characters, each with one decimal number behind the decimal point. Leading characters are blanks.
For reading you don't need the .1 info at all, just read a floating point number from those 7 characters.
You guessed the meaning of A4 (string of four characters) and 1X (one blank) correctly.
In Fortran, so-called data edit descriptors (which format the input or output of data) may have repeat specifications.
In the format (A4,1X,3F7.1) the data edit descriptors are A4 and F7.1. Only F7.1 has a repeat specification (the number before the F). This simply means that the format is as though the descriptor appeared repeated: like F7.1, F7.1, F7.1. With a repeat specification of 1, or not given, there is just the single appearance.
The format of the question, then, is like
(A4,1X,F7.1,F7.1,F7.1)
This format is one that is covered by the rules provided in one of the images of the question. In particular, the aspect of repeat specification is given in rule 2 with the corresponding example of rule 3.
Further, in Fortran proper, a repeat count specifier may also be * as special case: that's like an exceptionally large repeat count. *(F7.1) would be like F7.1, F7.1, F7.1, .... I see no indication that this is supported by HLM but if this is needed a very large repeat count may be given instead.
In 1X the 1 isn't a repeat specification but an integral, and necessary, part of the position edit descriptor.
Procedure for making MDM file from excel for HLM:
-Make sure ALL the characters in ALL the columns line up
Select a column, then right click and select Format Cells
Then click on 'Custom' and go to the 'Type' box and enter the number
of 0s you need to line everything up
-Remove all the tabs from the document and replace them with spaces.
Open the document in word and use find and replace
-To save the document as .dat
First save it as .txt
Then open it in Notepad and save it as .dat
To enter the data format (FORTRAN-Style)
The program wants to read the data file space by space, so you have to specify it perfectly so that it reads the whole set properly.
If something is off, even by a single space, then your descriptive stats will be wonky compared to if you check them in another program.
Enclose the code with brackets ()
Divide the entries with commas ,
-Need ID column for all levels
ID column needs to be sorted so that it is in order from smallest to
largest
Use A# with # being the number of characters in the ID
Use an X1 to
move from the ID to the next column
-Need to say how many characters are needed in each column
Use F
After F is the number of characters needed for that column -Use F# (#= number)
There need to be enough character spaces to provide one 'gap' space
between each column
There need to be enough to character spaces to allow for the decimal
As part of the F you need to specify the number of decimal places
You do this by adding a decimal point after the F number and then a
number to represent the spaces you need -F#.#
You can use a number in front of the F so as to 'repeat' it. Not
necessary though. -#F#.#
All in all, it should look something like this:
(A4,X1,F4.0,F5.1)
Helpful links:
https://books.google.de/books?id=VdmVtz6Wtc0C&pg=PA78&lpg=PA78&dq=data+format+fortran+style+hlm&source=bl&ots=kURJ6USN5e&sig=fdtsmTGSKFxn04wkxvRc2Vw1l5Q&hl=en&sa=X&ved=0ahUKEwi_yPurjYrYAhWIJuwKHa0uCuAQ6AEIPzAC#v=onepage&q&f=false
http://www.ssicentral.com/hlm/help6/error/Problems_creating_MDM_files.pdf
http://www.ssicentral.com/hlm/help7/faq/FAQ_Format_specifications_for_ASCII_data.pdf
The program can run, I am not sure how to use open() and save the data in another external file name output.txt. My questions are stated below - please have a look and help.
program start
implicit none
integer ::n
real(kind=8)::x,h,k
real(kind=8),external:: taylorq
x=1.0
n=20
h=exp(x)
k=taylorq(x,n)
open(10,'output.txt') ----------- *question1:(when should i put this open file?)*
write(*,*)"The exact value=",h
write(*,*)"The approximate value=",k
write(*,*)"The error=",h-k
end program start
function taylorq(x,n)
implicit none
integer::n,i
real(kind=8):: x,taylor,taylor2,taylorq,h
h=exp(x)
taylor=1.
taylor2=taylor
write(*,*)"i exact appro error"-----------question2:(actually I want to draw a table with subtitle i, exact, appro, error in each column, is there a nice way to arrange them like eg.we can use %5s)
do i=1,n
taylor=taylor*x/i
taylor2=taylor2+taylor
write(10,*)i,h,taylor2,taylor2-h --------question3:*(I want to save the data written here into file output.txt)*
end do
close(10)
taylorq=taylor2
end function taylorq
1. where to open
You should put open(10,...) so it executes before any write(10,...) -- or read(10,...) if this was input.
Since your writes occur in the function taylorq, you should open() before the statement that calls taylorq.
For programs that do very large computations, which Fortran is suited/famous for, it is often best to do
all file open's very near the beginning of the program, so that if there is a problem opening any file,
it is caught and fixed without wasting hours or days of work. But your program is much simpler than that.
2. formatting
Yes, Fortran can do formatted output -- and also formatted input. Instead of a text string with
interpolated specifiers (like C and the C part of C++, and Java, and awk and perl and shell) it uses specifiers
with optionally interpolated text values, and the specifiers are written with the format letter on
the left followed by the width (almost always) and other parameters (sometimes).
You can either put the format directly in the WRITE (or READ) statement, or in a separate FORMAT
statement referred to by its label in the I/O statement.
write (10, '(I4,F10.2,F10.2,F10.2)' ) i,h,taylor2,taylor2-h
or
write (10, 900) i,h,taylor2,taylor2-h
! this next line can be anywhere in the same program-unit
900 format (I4,F10.2,F10.2,F10.2)
Unlike C-family languages, Fortran will always output the specified width; if the value doesn't fit,
it prints asterisks ***** instead of forcing the field wider (and thus misaligned) (or truncating as
COBOL does!). Your series grows fast enough you might want to use scientific notation like E10.3.
(The format letters can be in either case, but I find them easier to read in upper. YMMV.)
There are many, MANY, more options. Any textbook or your compiler manual should cover this.
I am writing some simple output in fortran, but I want whitespace delimiters. If use the following statement, however:
format(A20,ES18.8,A12,ES18.8)
I get output like this:
p001t0000 3.49141273E+01obsgp_oden 1.00000000E+00
I would prefer this:
p001t0000 3.49141273E+01 obsgp_oden 1.00000000E+00
I tried using negative values for width (like in Python) but no dice. So, is there a way to left-justify the numbers?
Many thanks in advance!
There's not a particularly beautiful way. However, using an internal WRITE statement to convert the number to a text string (formerly done with an ENCODE statement), and then manipulating the text may do what you need.
Quoting http://rsusu1.rnd.runnet.ru/develop/fortran/prof77/node168.html
An internal file WRITE is typically
used to convert a numerical value to a
character string by using a suitable
format specification, for example:
CHARACTER*8 CVAL
RVALUE = 98.6
WRITE(CVAL, '(SP, F7.2)') RVALUE
The WRITE statement will fill the
character variable CVAL with the
characters ' +98.60 ' (note that there
is one blank at each end of the
number, the first because the number
is right-justified in the field of 7
characters, the second because the
record is padded out to the declared
length of 8 characters).
Once a number has been turned into a
character-string it can be processed
further in the various ways described
in section 7. This makes it possible,
for example, to write numbers
left-justified in a field, ...
This is easier with Fortran 95, but still not trivial. Write the number or other item to a string with a write statement (as in the first answer). Then use the Fortran 95 intrinsic "ADJUSTL" to left adjust the non-blank characters of the string.
And really un-elegant is my method (I program like a cave woman), after writing the simple Fortran write format (which is not LJ), I use a combination of Excel (csv) and ultraedit to remove the spaces effectively getting the desired LJ followed directly by commas (which I need for my specific import format to another software). BF
If what you really want is whitespace between output fields rather than left-justified numbers to leave whitespace you could simply use the X edit descriptor. For example
format(A20,4X,ES18.8,4X,A12,4X,ES18.8)
will insert 4 spaces between each field and the next. Note that the standard requires 1X for one space, some of the current compilers accept the non-standard X too.
!for left-justified float with 1 decimal.. the number to the right of the decimal is how many decimals are required. Write rounds to the desired decimal space automatically, rather than truncating.
write(*, ['(f0.1)']) RValue !or
write(*, '(f0.1)') RValue
!for left-justified integers..
write(*, ['(i0)']) intValue !or
write(*, '(i0)') RValue
*after feedback from Vladimir, retesting proved the command works with or without the array brackets