Механика. Афанасьев А.Д. - 22 стр.

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22
Приложение 5
Погрешности при косвенных измерениях
Вид функции Абсолютная
погрешность
Относительная погрешность
y
x
z
+
=
y
x
+
=
yx
yx
z
+
+
=ε
y
x
z
=
y
x
+
=
yx
yx
z
+
+
=ε
xy
z
=
x
y
y
x
+
=
y
y
x
x
yxz
+
=+= εεε
y
x
z =
2
y
xyyx
z
+
=
y
y
x
x
yxz
+
=+= εεε
n
x
z
=
x
nx
n
=
1
x
x
nn
xz
== εε
n
xz =
n
n
xn
x
z
1
=
nx
x
n
xz
== εε
1
yx
z
11
+=
22
y
y
x
x
z
+
=
)(
22
yxxy
yxxy
z
z
z
+
+
=
=ε
x
f
sin
=
x
x
f
=
cos
xctgx
f
=
ε
x
f
cos
=
x
x
f
=
sin
xtgx
f
=
ε
tgx
f
=
x
x
f
2
cos
=
x
x
f
2
sin
2
=ε
x
f lg
=
x
x
f
=
10ln
x
x
x
f
=
lg
10ln
ε
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                                                                                   Приложение 5

                  Погрешности при косвенных измерениях
                 Вид функции              Абсолютная            Относительная погрешность
                                          погрешность
                z = x+ y           ∆z = ∆x + ∆y                     ∆x + ∆y
                                                               εz =
                                                                     x+ y
                z = x− y           ∆z = ∆x + ∆y                     ∆x + ∆y
                                                               εz =
                                                                     x+ y
                z = xy             ∆z = x∆y + y∆x                                ∆x ∆y
                                                               εz =εx +εy =         +
                                                                                  x   y
                     x             ∆z =
                                          x∆y + y∆x                              ∆x ∆y
                z=                                             εz =εx +εy =         +
                     y                       y2                                   x   y
                z = xn             ∆z = nx n −1∆x                             ∆x
                                                               ε z = nε x = n
                                                                               x
                z=n x                           ∆x                   1       ∆x
                                   ∆z =                        εz = εx =
                                          n x n −1
                                            n                        n       nx
                     1 1                  ∆x ∆y                      ∆z ∆xy 2 + ∆yx 2
                z=    +            ∆z =     +
                                          x2 y2                εz =     =
                     x y                                              z     xy ( x + y )
                 f = sin x         ∆f = cos x∆x                ε f = ctgx∆x
                 f = cos x         ∆f = sin x∆x                ε f = tgx∆x
                 f = tgx           ∆f =
                                            ∆x                          2∆x
                                                               εf =
                                          cos 2 x                     sin 2 x
                 f = lg x                 ln 10∆x                     ln 10 ∆x
                                   ∆f =                        εf   =       ⋅
                                              x                        lg x x




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