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# And because most libm pow() functions special-case integer powers.
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# And because most libm pow() functions special-case integer powers.
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10^-(324:307-0.01)/10^0.01
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10^-(324:307-0.01)/10^0.01
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# IEC60559 mandates this, but C99/C11 do not.
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# IEC60559 mandates this, but C99/C11 do not.
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# Mingw-w64 did not do so in v 2.0.1
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# Mingw-w64 did not do so in v 2.0.1
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x <- 0*(-1) # negative zero
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(x <- 0*(-1)) # negative zero (prints as '0' in R on purpose!)
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sqrt(x)
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rt_0 <- sqrt(x) # ditto  -- but sprintf() shows "-0" :
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sprintf("%g, rt = %g, .^2 = %g", x, sqrt(x), x^2)
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sprintf("%g, rt = %g, .^2 = %g", x, sqrt(x), x^2)
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stopifnot(exprs = {
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identical(x, sqrt(x))
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    identical(1/ x, -Inf)
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    identical(1/-x, +Inf)
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    identical(x, -x,) # default num.eq=TRUE  ==> -0 "identical" 0
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    ! identical(x, -x,    num.eq=FALSE) # but not bitwise identical
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    identical(x, sqrt(x), num.eq=FALSE) # sqrt(-0) == -0
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    identical(-x, x^2,    num.eq=FALSE) # (-0)^2   == +0 = --0
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})