runtime: Inconsistency Multiplication, Division, and Addition Result #51031
Description
What version of Go are you using (go version)?
$ go version go version go1.17.6 windows/amd64
Does this issue reproduce with the latest release?
What operating system and processor architecture are you using (go env)?
go env Output
$ go env set GO111MODULE= set GOARCH=amd64 set GOBIN= set GOCACHE=C:\Users\user\AppData\Local\go-build set GOENV=C:\Users\user\AppData\Roaming\go\env set GOEXE=.exe set GOEXPERIMENT= set GOFLAGS= set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOINSECURE= set GOMODCACHE=C:\Users\user\go\pkg\mod set GONOPROXY= set GONOSUMDB= set GOOS=windows set GOPATH=C:\Users\user\go set GOPRIVATE= set GOPROXY=https://proxy.golang.org,direct set GOROOT=C:\Program Files\Go set GOSUMDB=sum.golang.org set GOTMPDIR= set GOTOOLDIR=C:\Program Files\Go\pkg\tool\windows_amd64 set GOVCS= set GOVERSION=go1.17.6 set GCCGO=gccgo set AR=ar set CC=gcc set CXX=g++ set CGO_ENABLED=1 set GOMOD=C:\Users\user\Documents\interview-codes\go.mod set CGO_CFLAGS=-g -O2 set CGO_CPPFLAGS= set CGO_CXXFLAGS=-g -O2 set CGO_FFLAGS=-g -O2 set CGO_LDFLAGS=-g -O2 set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=C:\Users\user\AppData\Local\Temp\go-build2510967983=/tmp/go-build -gno-record-gcc-switches
What did you do?
What did you expect to see?
I thought that c must be eqal to d
What did you see instead?
In another case i get correct results just like this
but the arithmetic give difference results by this formula
I got same issue with division and addition
test codes
func c1() {
a := 0.61 * 275.0
b := 0.62 * 275.0
c := 0.63 * 275.0
d := 0.64 * 275.0
e := 0.65 * 275.0
f := 0.66 * 275.0
g := 0.67 * 275.0
h := 0.68 * 275.0
i := 0.69 * 275.0
fmt.Printf("%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n", a, b, c, d, e, f, g, h, i)
}
func c2() {
z := 275.
a := 0.61 * z
b := 0.62 * z
c := 0.63 * z
d := 0.64 * z
e := 0.65 * z
f := 0.66 * z
g := 0.67 * z
h := 0.68 * z
i := 0.69 * z
fmt.Printf("%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n", a, b, c, d, e, f, g, h, i)
}
func c3() {
for i := 0; i < 10; i++ {
a := float64(i)/100 + 0.5
fmt.Printf("i = %d; a = %g\n", i, a)
}
}
func c4() {
z := 0.5
a := 0.01 + z
b := 0.02 + z
c := 0.03 + z
d := 0.04 + z
e := 0.05 + z
f := 0.06 + z
g := 0.07 + z
h := 0.08 + z
i := 0.09 + z
fmt.Printf("%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n", a, b, c, d, e, f, g, h, i)
}
func c5() {
a := 0.01 + 0.5
b := 0.02 + 0.5
c := 0.03 + 0.5
d := 0.04 + 0.5
e := 0.05 + 0.5
f := 0.06 + 0.5
g := 0.07 + 0.5
h := 0.08 + 0.5
i := 0.09 + 0.5
fmt.Printf("%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n%g\n", a, b, c, d, e, f, g, h, i)
}