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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.
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So a "single precision" float would fit in one register, while a "double precision" float would require two registers.
Single-precision floating-point format uses 32 bits of computer memory and can represent a wide range of numerical values. Often referred to as FP32, this format is best used for calculations that won't suffer from a bit of approximation.
In single-precision, 32-bit format, one bit is used to tell whether the number is positive or negative. Eight bits are reserved for the exponent, which (because it's binary) is 2 raised to some power. The remaining 23 bits are used to represent the digits that make up the number, called the significand.
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.
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In addition to the hardware view, on most systems the 32-bit format was used to implement the Fortran "real" type, and the 64 bit format to implement the Fortran "double precision" type.
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