type Double
| Since computer memory is limited, you cannot store numbers with infinite precision, no matter whether you use binary fractions or decimal ones: at some point you have to cut off. But how much accuracy is needed? And where is it needed? How many integer digits and how many fraction digits? To an engineer building a highway, it does not matter whether it’s 10 meters or 10.0001 meters wide - his measurements are probably not that accurate in the first place. To someone designing a microchip, 0.0001 meters (a tenth of a millimeter) is a huge difference - But he’ll never have to deal with a distance larger than 0.1 meters. A physicist needs to use the speed of light (about 300000000) and Newton’s gravitational constant (about 0.0000000000667) together in the same calculation. To satisfy the engineer and the chip designer, a number format has to provide accuracy for numbers at very different magnitudes. However, only relative accuracy is needed. To satisfy the physicist, it must be possible to do calculations that involve numbers with different magnitudes. Basically, having a fixed number of integer and fractional digits is not useful - and the solution is a format with a floating point. http://floating-point-gui.de/formats/fp/ |
In C++, the type double is the default floating point type.
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