信息与通信的数学基础——第一次实验(2)
文章目录1. 求下列各式的微分2. 函数f(z)=z∣z∣2f(z)=z|z|^2f(z)=z∣z∣2在何处可导?何处解析?3. 求解下列方程4. 设f(z)为解析函数,求系数a,b,c,d的值5. 计算积分1. 求下列各式的微分(1)1+ez1+e^z1+ezf = 1 + E^zD[f, z](2)sinz+cosz\sin{z}+\cos{z}sinz+coszf = Sin[z] +
文章目录
1. 求下列各式的微分
(1) 1 + e z 1+e^z 1+ez
f = 1 + E^z
D[f, z]
(2) sin z + cos z \sin{z}+\cos{z} sinz+cosz
f = Sin[z] + Cos[z]
D[f, z]
2. 函数 f ( z ) = z ∣ z ∣ 2 f(z)=z|z|^2 f(z)=z∣z∣2在何处可导?何处解析?
Clear[f]
Clear[z]
$Assumptions = x \[Element] Reals
$Assumptions = y \[Element] Reals
z = x + I*y;
f = z*(Abs[z])^2;
u = ComplexExpand[Re[f]]
v = ComplexExpand[Im[f]]
dux = D[u, x]
duy = D[u, y]
dvx = D[v, x]
dvy = D[v, y]
sol = Solve[dux == dvy && duy + dvx == 0, {x, y}]
3. 求解下列方程
(1) ln z = π i 2 \ln z = \frac{\pi i}{2} lnz=2πi
Clear[z];
sol1 = Solve[Log10[z] - I*Pi / 2 == 0, z]
Reduce[Log10[z] - I*Pi / 2 == 0, z]
(2) 1 + e z = 0 1+e^z=0 1+ez=0
Clear[z];
sol2 = Reduce[1 + E^z == 0, z]
(3) e z − 1 − 3 i = 0 e^z-1-\sqrt{3}i = 0 ez−1−3i=0
Clear[z];
sol3 = Reduce[E^z - 1 - I*Sqrt[3] == 0, z]
4. 设f(z)为解析函数,求系数a,b,c,d的值
f ( z ) = a y 3 + b x 2 y + i ( x 3 + c x y 2 ) f(z)=ay^3+bx^2y+i(x^3+cxy^2) f(z)=ay3+bx2y+i(x3+cxy2)为解析函数
Clear[x];
Clear[y];
Clear[u];
Clear[v];
u[x_, y_] := a*y^3 + b*x^2*y;
v[x_, y_] := x^3 + c*x*y^2;
dux = D[u[x, y], x]
duy = D[u[x, y], y]
dvx = D[v[x, y], x]
dvy = D[v[x, y], y]
Solve[2*b - 2*c == 0 && b + 3 == 0 && 3 a + c == 0, {a, b, c}]
5. 计算积分
(1) ∫ ∣ z ∣ = 1 d z z \int_{|z|=1} \frac{dz}{z} ∫∣z∣=1zdz
方法一:积分法
Integrate[I*E^(I*theta) / E^(I*theta), {theta, 0, 2*Pi}]
方法二:留数求解法
Residue[1 / z, {z, 0}]*2*Pi*I
(2) ∫ ∣ z ∣ = 1 d z ∣ z ∣ \int_{|z|=1} \frac{dz}{|z|} ∫∣z∣=1∣z∣dz
方法一:积分法
Integrate[I*E^(I*theta) / Abs[E^(I*theta)], {theta, 0, 2*Pi}]
方法二:留数求解法
Residue[1 / Norm[z], {z, 0}]*2*Pi*I
6. 求隐函数的导数或偏导数
(1) ln x 2 + y 2 = arctan y x \ln{\sqrt{x^2+y^2}}=\arctan{\frac{y}{x}} lnx2+y2=arctanxy
Clear[x];
Clear[y];
Clear[u];
Clear[v];
D[Log10[Sqrt[x^2 + y^2]] - ArcTan[y/x] == 0, y, NonConstants -> x]
% /. D[x, y, NonConstants -> {x}] -> x'
Solve[%, x']
(2) x = u cos v u , y = u sin v u x=u\cos{\frac{v}{u}},y=u\sin{\frac{v}{u}} x=ucosuv,y=usinuv,求 ∂ u ∂ x , ∂ u ∂ y , ∂ v ∂ x , ∂ v ∂ y \frac{\partial u}{\partial x},\frac{\partial u}{\partial y},\frac{\partial v}{\partial x},\frac{\partial v}{\partial y} ∂x∂u,∂y∂u,∂x∂v,∂y∂v
F1 = x1 - u1*Cos[v1/u1];
F2 = y1 - u1*Sin[v1/u1];
F1x = D[F1, x1]
F1u = D[F1, u1]
F1y = D[F1, y1]
F1v = D[F1, v1]
F2x = D[F2, x1]
F2y = D[F2, y1]
F2u = D[F2, u1]
F2v = D[F2, v1]
u2x = -(F1x*F2v - F1v*F2x)/(F1u*F2v - F1v*F2u)
u2y = -(F1y*F2v - F1v*F2y)/(F1u*F2v - F1v*F2u)
v2x = -(F1u*F2x - F1x*F2u)/(F1u*F2v - F1v*F2u)
v2y = -(F1u*F2y - F1y*F2u)/(F1u*F2v - F1v*F2u)

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