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What is the purpose of NaN?
Quiet NaNs are used to propagate errors resulting from invalid operations or values. Signaling NaNs can support advanced features such as mixing numerical and symbolic computation or other extensions to basic floating-point arithmetic.
What is NaN boxing?
The way NaN-boxing works is when you have non-float datatypes (pointers, integers, booleans) you store them in the payload, and use the top bits to encode the type of the payload. This means that we can store every value in the language in 64 bits.
Is NaN a method?
isNaN() method determines whether a value is NaN (Not-A-Number). This method returns true if the value is of the type Number, and equates to NaN. isNaN() does not convert the values to a Number, and will not return true for any value that is not of the type Number.
What is the payload of NaN boxing in C?
NaN-boxing is a way to store various information in unused NaN-space in the IEEE754 representation. Any value with the top 13 bits set represents a quiet NaN. The remaining bits are called the ‘payload’. NaNs produced by hardware and C-library functions typically produce a payload of zero.
What’s the purpose of NaN boxing in 64 bits?
NaN-boxing is morally equivalent to using tagged unions to represent values of any type. It optimizes for fast floating-point operations, and for allowing a larger amount of meaningful values to be represented in 64 bits.
What’s the advantage of NaN boxing in JavaScript?
The NaN approach stores everything as doubles, and reuses the unused portion of NaN for the extra storage. The advantage over the union method is that we save the type field. If it’s a valid double, it’s a double otherwise the mantissa is a pointer to the actual object. Remember, this is every javascript object.
What are the disadvantages of NaN boxing in Lua?
The disadvantage is that small values like numbers get stored as boxed values, So your little 5 gets stored as a block of memory somewhere. So this leads us to the union approach, which is used by Lua. Instead of a PyObject*, each value is a struct which one field to specify the type, and then a union of all the different supported types.