HP-15c Overflow question - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: Not HP Calculators (/forum-7.html) +--- Forum: Not quite HP Calculators - but related (/forum-8.html) +--- Thread: HP-15c Overflow question (/thread-17400.html) HP-15c Overflow question - agarza - 08-27-2021 01:21 PM Is it normal that after an overflow, the display keeps blinking? I mean, I can do normal operations and the display keeps blinking until I press the clear button. I have tried this only on emulators. Not on the real thing. RE: HP-15c Overflow question - rprosperi - 08-27-2021 07:14 PM Yes, a real 15C behaves exactly this way. It's a bit strange behavior, but presumably done to force the user to acknowledge something 'crashed'. Turning off/on also halts the blinking. RE: HP-15c Overflow question - Albert Chan - 08-27-2021 09:03 PM Intersestingly, modern computer may have wider exponent range for intermediate calculations. Code: ```#include  #include  int main(int argc, char **argv) {     double x = strtod(argv[1], NULL);     double y = strtod(argv[2], NULL);     printf("x, y = %g, %g\n", x, y);     printf("x/(x*x+y*y) = %g\n", x/(x*x+y*y));     return 0; }``` > test 1e200 1e220 x, y = 1e+200, 1e+220 x/(x*x+y*y) = 1e-240 > test 1e-200 1e-220 x, y = 1e-200, 1e-220 x/(x*x+y*y) = 1e+200 Without the wider exponent range, 1st example underflow to 0, 2nd overflow to Inf lua> function f(x,y) return x / (x*x+y*y) end lua> f(1e200, 1e220) 0 lua> f(1e-200, 1e-220) Inf see Problems due to wider expoenent range RE: HP-15c Overflow question - agarza - 08-28-2021 12:07 AM (08-27-2021 07:14 PM)rprosperi Wrote:  Yes, a real 15C behaves exactly this way. It's a bit strange behavior, but presumably done to force the user to acknowledge something 'crashed'. Turning off/on also halts the blinking. Thanks for the info. RE: HP-15c Overflow question - C.Ret - 08-28-2021 06:13 AM Bob Prosperi indicate the two main way to get ride off the erroneous screen blinking conditions by pressing the [← ] key to clear the display or the [ ON ] key to turn off the calculator. A third way to stop the "blinking" display after overflow is to clear the error flag indicator by typing [CF][ 9 ]. In program, you can also test this specific flag to detect a "crash" and branch to an alternate code. Oppositely, you can turn on the "blinking screen" by setting flag 9 on to warn the user of a specific situation or suspicious result. RE: HP-15c Overflow question - agarza - 08-28-2021 06:54 PM (08-28-2021 06:13 AM)C.Ret Wrote:  Bob Prosperi indicate the two main way to get ride off the erroneous screen blinking conditions by pressing the [← ] key to clear the display or the [ ON ] key to turn off the calculator. A third way to stop the "blinking" display after overflow is to clear the error flag indicator by typing [CF][ 9 ]. In program, you can also test this specific flag to detect a "crash" and branch to an alternate code. Oppositely, you can turn on the "blinking screen" by setting flag 9 on to warn the user of a specific situation or suspicious result. Very Interesting.