Is there a tool to know whether a value has an exact binary representation as a floating point variable?

by

Here’s a Python snippet that does exactly what you ask for; it needs Python 2.7 or Python 3.x. (Earlier versions of Python are less careful with floating-point conversions.)

import decimal, sys
input = sys.argv[1]
if decimal.Decimal(input) == float(input):
    print("Exactly representable")
else:
    print("Not exactly representable")

Usage: after saving the script under the name ‘exactly_representable.py’,

mdickinson$ python exactly_representable.py 1.25
Exactly representable
mdickinson$ python exactly_representable.py 0.1
Not exactly representable
mdickinson$ python exactly_representable.py 1e22
Exactly representable
mdickinson$ python exactly_representable.py 1e23
Not exactly representable

More Related Contents:

  1. Read and write to binary files in C?
  2. what the output of this code and why?
  3. printf anomaly after “fork()”
  4. How do I restrict a float value to only two places after the decimal point in C?
  5. How to make child process die after parent exits?
  6. What is time_t ultimately a typedef to?
  7. What is the equivalent to Posix popen() in the Win32 API?
  8. How do I execute an external program within C code in Linux with arguments?
  9. Measure time in Linux – time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?
  10. stdout thread-safe in C on Linux?
  11. What operations and functions on +0.0 and -0.0 give different arithmetic results?
  12. Is malloc/free a syscall or a library routine provided by libc?
  13. Building a kernel module from several source files which one of them has the same name as the module
  14. What parts of this HelloWorld assembly code are essential if I were to write the program in assembly?
  15. Are file descriptors shared when fork()ing?
  16. Detecting 64bit compile in C
  17. how to call function in executable from my library?
  18. How does sig_atomic_t actually work?
  19. Interprocess mutex with pthreads
  20. Comparing floating point numbers in C
  21. How to make backtrace()/backtrace_symbols() print the function names?
  22. Count number of digits after `.` in floating point numbers?
  23. Write to .txt file?
  24. Do forked child processes use the same semaphore?
  25. Implementation of multiple pipes in C
  26. Trouble with float on C [duplicate]
  27. In C, what’s the size of stdout buffer?
  28. C printf using %d and %f
  29. Why do you need an explicit `-lm` compiler option? [duplicate]
  30. C fundamentals: double variable not equal to double expression?

Leave a Comment