6.4 SQRT function

SQRT

## function (x) 
## {
##     if (x < 0) {
##         warning("NaN produced")
##         return(NaN)
##     }
##     else if (x == 0) {
##         return(0)
##     }
##     else {
##         Norm = NORM(x)
##         x1 = Norm[1]
##         xexp = Norm[2]
##         sqrt2 = 1.4142135623731
##         y = (-0.1984742 * x1 + 0.8804894) * x1 + 0.3176687
##         y = 0.5 * (y + x1/y)
##         y = y + x1/y
##         x1 = 0.25 * y + x1/y
##         if (xexp%%2 == 1) {
##             x1 = x1 * sqrt2
##             xexp = xexp - 1
##         }
##         Res = DENORM(c(x1, xexp/2))
##         return(Res)
##     }
## }
## <bytecode: 0x000001e2acdf2a98>
## <environment: namespace:math>

Practice Script

format(SQRT(0.5), digits=22)

## [1] "0.707106781186547461715"

format(sqrt(0.5), digits=22)

## [1] "0.7071067811865475727373"

# Closest value of sqrt(.5) = .70710 67811 86547 52440 in 20 digits

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