Re: EXC_ARITHMETIC when writing a floating point variable

Re: EXC_ARITHMETIC when writing a floating point variable

[Dominique Dhumieres]

Richard,

Usual comment: give a nonworking reduced test case!

You can also use -Wall and -Wuninitialized (with -O
for the later). Try to find the minimal set of options
tha trigger the problem: do you really need
-fdefault-double-8 -fdefault-integer-8 -fdefault-real-8?
If yes, are not you passing REAL variables to procs
expecting a REAL(4) (old timing procs are good candidates)?

You can also use valgrind on Mac OS 10.6.4 (I build it
with fink, but it may exist on macports).

If none of the above works, you can mail me the code
and I can have a look.

Cheers,

Dominique

Re: EXC_ARITHMETIC when writing a floating point variable

[Richard Daal]

Dear all,

Thank you very much for your feedback, which finally led to the
solution of the problem. As Steve pointed out in his reply, I got what
I wanted. :-)

The problem I encountered last week is caused by: -ffpe-trap=precision

It does not need any complex code to produce the floating point
exception (EXC_ARITHMETIC). Just:

   double precision :: Test
   Test = 123.45
   write(*, *) Test


With kind regards

Richard


2010/10/31 Richard Daal <rd.daal@gmail.com>:
> Dear all,
>
> I am struggling with a problem for some time now, where I do not know
> how to proceed. I would greatly appreciate, if I could get some
> advise.
>
> I try to write a double precision variable "Test = 3.456" with
> "write(*, *) Test" to the terminal.
> That produces a floating point exception. With gdb, I get the
> following error message:
> "Program received signal EXC_ARITHMETIC, Arithmetic exception.
> 0x000000001001c8132 in __dtoa ()"
>
> However, at some place in the code double precision variables of an
> allocatable array that belongs to a derived type are written to the
> terminal and this works fine. When removing the write statement that
> produces the error, the program works fine.
> I do not understand, what could go wrong with this "write" statement?
> How could I check what the problem is? Its a relatively complex code.
>
> I use the following flags with gfortran 4.5.1 (on Mac OS 10.6.4) for
> compilation:
> -ffree-form -fimplicit-none -frange-check -std=f2003
> -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fmax-errors=0
> -pedantic -Wall -fconvert=native -fbounds-check
> -fmax-stack-var-size=32768 -g -ffpe-trap=invalid,zero,
> overflow,underflow,precision,denormal
> ... and for linking:
> -arch_errors_fatal -arch x86_64 -g
>
> I thank you very much in advance for your help.
>
> With kind regards,
>
> Richard
>

Re: EXC_ARITHMETIC when writing a floating point variable

[Steve Kargl]

On Sun, Oct 31, 2010 at 04:55:50PM +0100, Richard Daal wrote:
> 
> I try to write a double precision variable "Test = 3.456" with
> "write(*, *) Test" to the terminal.
> That produces a floating point exception. With gdb, I get the
> following error message:
> "Program received signal EXC_ARITHMETIC, Arithmetic exception.
> 0x000000001001c8132 in __dtoa ()"

Well, what does EXC_ARITHMETIC mean?  This is OS specific! 

> -ffpe-trap=invalid,zero,overflow,underflow,precision,denormal

Looks like you got what you wanted.

-- 
Steve

Re: EXC_ARITHMETIC when writing a floating point variable

[Jerry DeLisle]

On 10/31/2010 08:55 AM, Richard Daal wrote:
> Dear all,
>
> I am struggling with a problem for some time now, where I do not know
> how to proceed. I would greatly appreciate, if I could get some
> advise.
>
> I try to write a double precision variable "Test = 3.456" with
> "write(*, *) Test" to the terminal.
> That produces a floating point exception. With gdb, I get the
> following error message:
> "Program received signal EXC_ARITHMETIC, Arithmetic exception.
> 0x000000001001c8132 in __dtoa ()"
>
> However, at some place in the code double precision variables of an
> allocatable array that belongs to a derived type are written to the
> terminal and this works fine. When removing the write statement that
> produces the error, the program works fine.
> I do not understand, what could go wrong with this "write" statement?
> How could I check what the problem is? Its a relatively complex code.
>
> I use the following flags with gfortran 4.5.1 (on Mac OS 10.6.4) for
> compilation:
> -ffree-form -fimplicit-none -frange-check -std=f2003
> -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fmax-errors=0
> -pedantic -Wall -fconvert=native -fbounds-check
> -fmax-stack-var-size=32768 -g -ffpe-trap=invalid,zero,
> overflow,underflow,precision,denormal
> ... and for linking:
> -arch_errors_fatal -arch x86_64 -g
>
> I thank you very much in advance for your help..
>
> With kind regards,
>
> Richard
>

My first suggestion is don't use these:

  -fdefault-double-8 -fdefault-integer-8 -fdefault-real-8

It is better to use explicit kind specifications and set a parameter in the 
program for the kind type to use.

I suppose your code is legacy and does not have any easy way to do this. The 
only way that I can see that the write statement would fail like that is if the 
variable has been stomped on because something is out of bounds. Of course there 
coud be a real exception in __dtoa () which would be a bug.

Try eliminating chunks of code until the problem goes away.  This might give a hint.

Jerry

EXC_ARITHMETIC when writing a floating point variable

[Richard Daal]

Dear all,

I am struggling with a problem for some time now, where I do not know
how to proceed. I would greatly appreciate, if I could get some
advise.

I try to write a double precision variable "Test = 3.456" with
"write(*, *) Test" to the terminal.
That produces a floating point exception. With gdb, I get the
following error message:
"Program received signal EXC_ARITHMETIC, Arithmetic exception.
0x000000001001c8132 in __dtoa ()"

However, at some place in the code double precision variables of an
allocatable array that belongs to a derived type are written to the
terminal and this works fine. When removing the write statement that
produces the error, the program works fine.
I do not understand, what could go wrong with this "write" statement?
How could I check what the problem is? Its a relatively complex code.

I use the following flags with gfortran 4.5.1 (on Mac OS 10.6.4) for
compilation:
-ffree-form -fimplicit-none -frange-check -std=f2003
-fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fmax-errors=0
-pedantic -Wall -fconvert=native -fbounds-check
-fmax-stack-var-size=32768 -g -ffpe-trap=invalid,zero,
overflow,underflow,precision,denormal
... and for linking:
-arch_errors_fatal -arch x86_64 -g

I thank you very much in advance for your help.

With kind regards,

Richard