Hi, My questions is: How many machine cycles does it take a function of absolute value? The operation is for a number floating point.
That all depends on the function! And which memory model. Probably on the value also!! Are you referring to the Keil Library function abs() specifically?
Yes, function abs() of keil library
You could always use the uVision Performance Analyser to measure it - with a set of suitable test cases.
The execution speed of the fabs library routine is very fast because it only needs to clear a single bit in the floating-point value. Refer to the specification for floating-point numbers in the C51 manual. Jon