Matlab for循环，Python中的不同值
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我在matlab中有代码，我正尝试将其“重写”为Python。问题在于for循环的值不同。不幸的是我找不到解决方案。
问题在每个数组中都有值：nu元素中的thetamuM i。
在Python中，DTOR或RTOD是弧度，反之亦然。
对于两个代码n=30
----------------------------------------- Matlab： --- ----------------------------------
for t = 1:2
i=n+2;
h = i;
k=0;
z=2;
for j= 1:n-1
while (i<=h+n-k-1)
if (i==h)
if (i==node_number-1)
y(i)=0;
theta(i)=0;
M(i) = Me;
nu(i) =PrandtlMeyer(M(i),gamma);
mu(i)= asin(1/M(i))*180/pi;
mI = tand((mu(i-n+k)-theta(i-n+k)+mu(i))/2);
x(i)= (y(i-n+k)/mI)+x(i-n+k);
if (t==2)
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
else
y(i)=0;
theta(i)=0;
nu(i) = theta(i-n+k)+nu(i-n+k)+(1/(sqrt((M(i-n+k)^2)-1)-cotd(theta(i-n+k))));
M(i) = InversePrandtlMeyer(nu(i));
mu(i)= asin(1/M(i))*180/pi;
mI = tand((mu(i-n+k)-theta(i-n+k)+mu(i))/2);
x(i)= (y(i-n+k)/mI)+x(i-n+k);
if (t==2)
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
end
else if (i==h+1)
if (i==node_number)
mI = tand((theta(i-n+k)+theta(i))/2);
mII =tand((mu(i-1)+theta(i-1)+theta(i)+mu(i))/2);
x(i) = (y(i-1)-y(i-n+k)+(x(i-n+k)*mI)-(x(i-1)*mII))/(mI-mII);
y(i) = y(i-1)+((x(i)-x(i-1))*mII);
y1(z) = y(i-1)+((x(i)-x(i-1))*mII);
x1(z) = (y(i-1)-y(i-n+k)+(x(i-n+k)*mI)-(x(i-1)*mII))/(mI-mII);
theta(i) = theta(i-1);
nu(i) = nu(i-1);
M(i) = M(i-1);
mu(i)= asin(1/M(i))*180/pi;
z=z+1;
if (t==2)
plot([x(i-1) x(i)],[y(i-1) y(i)]);
hold on;
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
else
mI = tand((mu(i-n+k)-theta(i-n+k)+mu(i)-theta(i))/2);
mII = tand((mu(i)+theta(i)+mu(i-1))/2);
x(i) = (y(i-n+k)+(x(i-1)*mII)+(x(i-n+k)*mI))/(mII+mI);
y(i) = (x(i)-x(i-1))*mII;
nu(i) = (theta(i-n+k)+nu(i-n+k)+(nu(i-1)/2)+((1/(sqrt((M(i-n+k)^2)-1)-cotd(theta(i-n+k))))*((y(i)-y(i-n+k))/y(i-n+k))))/1.5;
theta(i)= (nu(i)-nu(i-1))/2;
M(i) = InversePrandtlMeyer(nu(i));
mu(i)= asin(1/M(i))*180/pi;
if (t==2)
plot([x(i-1) x(i)],[y(i-1) y(i)]);
hold on;
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
end
else if (i==h+n-k-1)
mI = tand((theta(i-n+k)+theta(i))/2);
mII =tand((mu(i-1)+theta(i-1)+theta(i)+mu(i))/2);
x(i) = (y(i-1)-y(i-n+k)+(x(i-n+k)*mI)-(x(i-1)*mII))/(mI-mII);
y(i) = y(i-1)+((x(i)-x(i-1))*mII);
y1(z)=y(i-1)+((x(i)-x(i-1))*mII);
x1(z) = (y(i-1)-y(i-n+k)+(x(i-n+k)*mI)-(x(i-1)*mII))/(mI-mII);
theta(i) = theta(i-1);
nu(i) = nu(i-1);
M(i) = M(i-1);
mu(i)= asin(1/M(i))*180/pi;
z=z+1;
if (t==2)
plot([x(i-1) x(i)],[y(i-1) y(i)]);
hold on;
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
else
mI = tand((mu(i-n+k)-theta(i-n+k)+mu(i)-theta(i))/2);
mII = tand((mu(i-1)+theta(i-1)+mu(i)+theta(i))/2);
x(i) = (y(i-n+k)-y(i-1)+(x(i-n+k)*mI)+(x(i-1)*mII))/(mII+mI);
y(i) = y(i-1)+((x(i)-x(i-1))*mII);
theta(i) = (theta(i-n+k)+nu(i-n+k)+theta(i-1)-nu(i-1)+((1/(sqrt((M(i-n+k)^2)-1)-cotd(theta(i-n+k))))*((y(i)-y(i-n+k))/y(i-n+k)))-((1/(sqrt((M(i-1)^2)-1)-cotd(theta(i-1))))*((y(i)-y(i-1))/y(i-1))))/2;
nu(i) = (theta(i-n+k)+nu(i-n+k)-theta(i-1)+nu(i-1)+((1/(sqrt((M(i-n+k)^2)-1)-cotd(theta(i-n+k))))*((y(i)-y(i-n+k))/y(i-n+k)))+((1/(sqrt((M(i-1)^2)-1)-cotd(theta(i-1))))*((y(i)-y(i-1))/y(i-1))))/2;
M(i) = InversePrandtlMeyer(nu(i));
mu(i)= asin(1/M(i))*180/pi;
if (t==2)
plot([x(i-1) x(i)],[y(i-1) y(i)]);
hold on;
plot([x(i-n+k) x(i)],[y(i-n+k) y(i)]);
hold on;
end
end
end
end
i = i+1;
end
k=k+1;
h=i;
end
end
以及Matlab“ theta”值的前几行：
0.4397 0.8793 1.3190 1.7587 2.1983 2.6380 3.0776 3.5173
3.9570 4.3966 4.8363 5.2760 5.7156 6.1553 6.5949 7.0346
7.4743 7.9139 8.3536 8.7933 9.2329 9.6726 10.1122 10.5519
10.9916 11.4312 11.8709 12.3106 12.7502 13.1899 13.1899 0
0.3032 0.7453 1.1877 1.6301 2.0725 2.5149 2.9572 3.3995
3.8418 4.2840 4.7262 5.1684 5.6106 6.0528 6.4951 6.9373
7.3795 7.8218 8.2641 8.7065 9.1488 9.5913 10.0337 10.4762
10.9188 11.3614 11.8041 12.2469 12.2469 0 0.2977 0.7407
1.1839 1.6271 2.0702 2.5133 2.9562 3.3991 3.8420 4.2848
4.7276 5.1704 5.6131 6.0559 6.4986 6.9414 7.3842 7.8270
----------------------------------------- Python： --- ----------------------------------
i = n + 1
h = i
k = 0
z = 1
for j in range(n-1):
while i <= h + n - k-1:
if i == h:
if i == node_number -1:
y[i] = 0
theta[i] = 0
M[i] = Me
nu[i] = PM(M[i], gamma)
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
mI = np.tan((mu[i - n + k] - theta[i - n + k] + mu[i]) / 2 * DTOR)
x[i] = (y[i - n + k] / mI) + x[i - n + k]
else:
y[i] = 0
theta[i] = 0
nu[i] = theta[i - n + k] + nu[i - n + k] + (1 / (np.sqrt((M[i - n + k]**2) - 1) - np.cos((theta[i - n + k])*DTOR)))
M[i] = InversePrandtlMeyer(nu[i])
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
mI = np.tan(((mu[i - n + k] - theta[i - n + k] + mu[i]) / 2) * DTOR)
x[i] = (y[i - n + k] / mI) + x[i - n + k]
elif i == h + 1:
if i == node_number:
mI = np.tan((theta[i - n + k] + theta[i]) / 2 * DTOR)
mII = np.tan((mu[i - 1] + theta[i - 1] + theta[i] + mu[i]) / 2 * DTOR)
x[i] = (y[i - 1] - y[i - n + k] + (x[i - n + k] * mI) - (x[i - 1] * mII)) / (mI - mII)
y[i] = y[i - 1] + ((x[i] - x[i - 1]) * mII)
y1[z] = y[i - 1] + ((x[i] - x[i - 1]) * mII)
x1[z] = (y[i - 1] - y[i - n + k] + (x[i - n + k] * mI) - (x[i - 1] * mII)) / (mI - mII)
theta[i] = theta[i - 1]
nu[i] = nu[i - 1]
M[i] = M[i - 1]
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
z = z + 1
else:
mI = np.tan((mu[i - n + k] - theta[i - n + k] + mu[i] - theta[i]) / 2 * DTOR)
mII = np.tan((mu[i] + theta[i] + mu[i - 1]) / 2 * DTOR)
x[i] = (y[i - n + k] + (x[i - 1] * mII) + (x[i - n + k] * mI)) / (mII + mI)
y[i] = (x[i] - x[i - 1]) * mII
nu[i] = (theta[i - n + k] + nu[i - n + k] + (nu[i - 1] / 2) + ((1 / (np.sqrt((M[i - n + k] ** 2) - 1) - np.cos((theta[i - n + k])*DTOR))) * ((y[i] - y[i - n + k]) / y[i - n + k]))) / 1.5
theta[i] = (nu[i] - nu[i - 1]) / 2
M[i] = InversePrandtlMeyer(nu[i])
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
elif i == h + n - k-1:
mI = np.tan((theta[i - n + k] + theta[i]) / 2 * DTOR)
mII = np.tan((mu[i - 1] + theta[i - 1] + theta[i] + mu[i]) / 2 * DTOR)
x[i] = (y[i - 1] - y[i - n + k] + (x[i - n + k] * mI) - (x[i - 1] * mII)) / (mI - mII)
y[i] = y[i - 1] + ((x[i] - x[i - 1]) * mII)
y1[z] = y[i - 1] + ((x[i] - x[i - 1]) * mII)
x1[z] = (y[i - 1] - y[i - n + k] + (x[i - n + k] * mI) - (x[i - 1] * mII)) / (mI - mII)
theta[i] = theta[i - 1]
nu[i] = nu[i - 1]
M[i] = M[i - 1]
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
z = z + 1
else:
mI = np.tan((mu[i - n + k] - theta[i - n + k] + mu[i] - theta[i]) / 2 * DTOR)
mII = np.tan((mu[i - 1] + theta[i - 1] + mu[i] + theta[i]) / 2 * DTOR)
x[i] = (y[i - n + k] - y[i - 1] + (x[i - n + k] * mI) + (x[i - 1] * mII)) / (mII + mI)
y[i] = y[i - 1] + ((x[i] - x[i - 1]) * mII)
theta[i] = (theta[i - n + k] + nu[i - n + k] + theta[i - 1] - nu[i - 1] + ((1 / (np.sqrt((M[i - n + k] ** 2) - 1) - np.cos((theta[i - n + k]) * DTOR))) * ((y[i] - y[i - n + k]) / y[i - n + k])) - ((1 / (np.sqrt((M[i - 1] ** 2) - 1) - np.cos((theta[i - 1])*DTOR))) * ((y[i] - y[i - 1]) / y[i - 1]))) / 2
nu[i] = (theta[i - n + k] + nu[i - n + k] - theta[i - 1] + nu[i - 1] + ((1 / (np.sqrt((M[i - n + k] ** 2) - 1) - np.cos((theta[i - n + k])*DTOR))) * ((y[i] - y[i - n + k]) / y[i - n + k])) + ((1 / (np.sqrt((M[i - 1] ** 2) - 1) - np.cos((theta[i - 1])*DTOR))) * ((y[i] - y[i - 1]) / y[i - 1]))) / 2
M[i] = InversePrandtlMeyer(nu[i])
mu[i] = np.arcsin(1 / M[i]) * 180 / np.pi
i = i + 1
k = k + 1
h = i
以及Python“ theta”值的前几行：
[ 0.43966268 0.87932536 1.31898804 1.75865072 2.1983134 2.63797608
3.07763876 3.51730144 3.95696412 4.3966268 4.83628948 5.27595216
5.71561484 6.15527752 6.5949402 7.03460288 7.47426556 7.91392824
8.35359092 8.7932536 9.23291628 9.67257896 10.11224165 10.55190433
10.99156701 11.43122969 11.87089237 12.31055505 12.75021773 13.18988041
13.18988041 0. 1.12391865 2.04904177 2.75249233 3.37815396
3.96686921 4.53558282 5.09310744 5.64490943 6.19500187 6.74690367
7.30431746 7.87186621 8.45626406 9.06871626 9.73089387 10.49343203
11.51563061 13.74816848 0.85949953 nan nan nan
nan nan nan nan nan nan
nan 0. 1.48303468 2.8885035 3.74795106 4.46269741
5.11686874 5.74107193 6.35015955 6.95312861 7.55674416 8.16737947
8.79250326 9.44272463 10.13594268 10.90840157 11.85472483 13.39395428
13.37483292 nan nan
答案
python计算的问题之一是它们很安静，通常是错误的这可能是为什么彼此不相等的原因之一您可以在此处找到有关它的更多信息：Is floating point math broken?
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