I need to make a Math.Sqrt calculation but it must support really big numbers so I'm trying to use BigInteger but Math.Sqrt doesn't support them.
Are there any other options? How can I do this calculation and result is double ?
Sample :
sqrt 5 = 2,2360679774997896964091736687313
sqrt 4789798765456456456 = xxxxx,xxxxxxxxxxx norm.
The easiest way is probably to run Newton's method for square roots starting with a double-precision initial guess.
To speed this up, notice that Newton's method doubles its precision with every iteration. You can double your precision with every iteration as well by keeping track of an int32 "exponent" together with your
BigInteger"mantissa", increasing the precision of the "mantissa" by a factor of two with each step until sufficient precision is reached.