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floating-pointdoubleieee-754single-precision

Why is a float "single precision"?


I'm curious as to why the IEEE calls a 32-bit floating-point number single precision. Was it just a means of standardization, or does 'single' actually refer to a single 'something'.

Is it simply a standardized level? As in, precision level 1 (single), precision level 2 (double) and so on? I've searched all over and found a great deal about the history of floating point numbers, but nothing that quite answers my question.


Solution

  • On the machine I was working on at the time, a float occupied a single 36 bit register. A double occupied two 36 bit registers. The hardware had separate instructions for operating on the 1 register and 2 register versions of the number. I don't know for certain that that's where the terminology came from, but it's possible.