Error Floating Point Exception Integer Divide By Zero
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vote favorite 2 Division by zero in a C program results in abnormal termination with the error message Floating point exception (core dumped). This is unsurprising for floating point division, but why does it say this when integer division by zero occurs? Does integer division actually use the FPU under the hood? (This is all on Linux under x86, by the way.) c divide-by-zero share|improve this question asked Jun 4 '13 floating point exception (core dumped) at 23:07 Taymon 11.7k43267 Worth noting that other non-POSIX operating systems (eg Windows) and the x86 hardware report different exceptions for integer and floating-point divide by zero. –Crashworks Jun 3 at 0:41 add a comment| 4 Answers 4 active oldest votes up vote 18 down vote accepted Does integer division actually use the FPU under the hood? No, Linux just generates SIGFPE in this case too (it's a legacy name whose usage has now been extended). Indeed, the Single Unix Specification defines SIGFPE as "Erroneous arithmetic operation". share|improve this answer edited Jun 4 '13 at 23:16 answered Jun 4 '13 at 23:10 Oliver Charlesworth 184k20364517 add a comment| up vote 3 down vote man signal mentions: Integer division by zero has undefined result. On some architectures it will generate a SIGFPE signal. (Also dividing the most negative integer by -1 may generate SIGFPE.) share|improve this answer answered Jun 4 '13 at 23:16 millimoose 27.2k54789 add a comment| up vote 1 down vote My guess at a historical explanation for this would be that the original unix hardware didn't generate a trap on integer division by zero, so the name SIGFPE made sense. (PDP assembly programmers, confirm?) Then later when the system was ported (or in the case of Linux, reimp
When computations go awry in your program, you may notice incorrect numbers in some output fields, even though your program continues to execute. Sometimes you may notice strings like INF and NaN in fields where linux signals only numbers should be; these indicate certain kinds of floating-point exceptions (FPEs). INF
Atoi
means "infinity" and NaN means "not a number." Sometimes it's hard to find where these FPEs occur in your code, but
Valgrind
you must find and fix them. They are useful only as diagnostics, and they harm performance since each FPE interrupts the processor on which it occurs. So how do you find where FPEs are occuring http://stackoverflow.com/questions/16928942/why-does-integer-division-by-zero-result-in-a-floating-point-exception in your code? Salting your code with print statements is hit-or-miss and invasive, and we do not recommend it. If you believe you have only a few FPEs, you are well advised to use a debugger like TotalView or dbx, which will often automatically point at the first FPE in your core file. But if you have many FPEs, weeding them out in this manner can be tedious. Error trapping https://www.cisl.ucar.edu/news/01/tips/0209.fpe.html An alternative and reliable method is called "trapping." By trapping, we mean setting a trap at your program's runtime that gets tripped when an FPE occurs, after which the program execution follows a prescribed course of your choice. This course is referred to as "handling" the error, where the handling you choose may cause the program to abort, print a diagnostic message, or provide a traceback. With certain methods of trapping, you can even provide a subroutine or function that changes the behavior of the floating-point arithmetic, though you should consult a numerical analyst about the consequences before handling errors in this manner. Since trapping and handling require extra processor time, you may wish to remove trapping/handling subroutine calls and compiler options after you have removed your program's FPEs. Both trapping and handling are implemented via "signals," and you often find their documentation under the broader topics of "signals" or "signal handling". All computers discussed in this article utilize IEEE binary floating-point arithmetic [1], with the exception of Cray, which uses Cray floating-point arithmetic. (Please consult a Cray Research CPU hardware reference manual if you need information about Cray's format.) Six floating-point error types There are six FPE types in the context of IEEE floating-point arithmetic. Underf
Sign in Pricing Blog Support Search GitHub https://github.com/clMathLibraries/clFFT/issues/159 This repository Watch 70 Star 326 Fork 122 clMathLibraries/clFFT Code Issues 9 Pull requests 1 Projects 0 Wiki Pulse Graphs New issue Floating point exception / integer division by zero #159 Closed tdd11235813 opened this Issue Aug 3, 2016 · 1 comment Projects floating point None yet Labels None yet Milestone No milestone Assignees No one assigned 2 participants tdd11235813 commented Aug 3, 2016 Hi, when using certain 2D transforms, a floating point exception occurs (both CPU and GPU), which actually seems to be an floating point exception integer division by zero. Some 2D examples (with code from pull request #158 ): x y Result 65536 64 OK 131072 2 FAIL 2 131072 OK 131072 64 FAIL 131072 128 FAIL 128 131072 FAIL 1048576 64 OK This also happens for clFFT-client -x x -y y -p 10 x y Result 65536 64 OK 131072 64 FAIL 1048576 64 OK 1048576 2 FAIL Environment cuda/7.5.18 opencl/1.2-4.4.0.117 gcc/5.3.0 clFFT/2.12.0 and clFFT/2.12.1 RHEL 6.7 GPU K20X and Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz Stacktrace Program received signal SIGFPE, Arithmetic exception. 0x00007ffff7d7d228 in StockhamGenerator::Kernel<(StockhamGenerator::Precision)0>::GenerateKernel (this=this@entry=0x7fffffff8020, str=..., Dev_ID=0x6bb928) at clFFT/src/library/generator.stockham.cpp:4164 4164 str += "\n\tfor(uint t=0; t<"; str += SztToStr(blockWidth/(blockWGS/workGroupSizePerTrans)); (gdb) bt #0 0x00007ffff7d7d228 in StockhamGenerator::Kernel<(StockhamGenerator::Precision)0>::GenerateKernel (this=this@entry=0x7fffffff8020, str=..., Dev_ID=0x6bb928) at clFFT/src/library/generator.stockham.cpp:4164 #1 0x00007ffff7d587bd in FFTGeneratedStockhamAction::generateKernel (this=this@entry=0x217c140, fftRepo=..., commQueueFFT=commQueueFFT@entry=0x1cf0668) at clFFT/src/library/generator.stock