英文:
MATLAB - "else" does not run after "if" condition is no longer true
问题
我遇到了一些困难，无法弄清楚为什么在条件sum(T(:,j)<Tm)==layers或T(:,j)<Tm不再成立后，“else”部分不会运行。
clc
clear all
rho = 0.9;
k = 0.0018;
cp = 1.92;
l = 0.1525;
layers = 10;
dx = l/layers;
z = l-(dx/2): - dx: dx/2;
time = 25;
dt = 1;
t = 1: dt: time;
T0 = 25;
Tm1 = 165;
Tm2 = 135;
X01 = 0.25;
X02 = 0.3;
F0 = 2.202;
F = zeros(1,length(t));
T = zeros(length(z), length(t));
n = 1;
modulatingcycles = 4;
Tm = Tm1*ones(length(z),1);
for i = 1:round(length(z)*X01/(X01+X02))
ind1 = randi([1 length(z)],1,1);
Tm(ind1) = Tm2;
end
for j = 1 : length(t)
if T(:,j)<Tm
F(j) = F0;
n = n + 1;
else
x = ceil((length(t) - n)/modulatingcycles);
y = n;
F(y:y+x) = F0/2;
F(y+x+1:y+x+x) = F0;
if j == y + x + x
y = y + x + x + 1;
end
end
for i = 1 : length(z)
T(i,j) = T (i,j) + T0 + ((F(j)*t(j))/(rho*cp*l)) + ((F(j)*l/k) * (3*(z(i)^2) - (l^2)) / (6*l^2));
end
}
英文:
I am having some trouble figuring out why my "else" section would not run after the condition sum(T(:,j)<Tm)==layers or T(:,j)<Tm is no longer true.
clc
clear all
rho = 0.9;
k = 0.0018;
cp = 1.92;
l = 0.1525;
layers = 10;
dx = l/layers;
z = l-(dx/2): - dx: dx/2;
time = 25;
dt = 1;
t = 1: dt: time;
T0 = 25;
Tm1 = 165;
Tm2 = 135;
X01 = 0.25;
X02 = 0.3;
F0 = 2.202;
F = zeros(1,length(t));
T = zeros(length(z), length(t));
n = 1;
modulatingcycles = 4;
Tm = Tm1*ones(length(z),1);
for i = 1:round(length(z)*X01/(X01+X02))
ind1 = randi([1 length(z)],1,1);
Tm(ind1) = Tm2;
end
for j = 1 : length(t)
if T(:,j)<Tm
%sum(T(:,j)<Tm)==layers
F(j) = F0;
n = n + 1;
else
x = ceil((length(t) - n)/modulatingcycles);
y = n;
F(y:y+x) = F0/2;
F(y+x+1:y+x+x) = F0;
if j == y + x + x
y = y + x + x + 1;
end
end
for i = 1 : length(z)
T(i,j) = T (i,j) + T0 + ((F(j)*t(j))/(rho*cp*l)) + ((F(j)*l/k) * (3*(z(i)^2) - (l^2)) / (6*l^2));
end
end
答案1
得分: 2
对于你提供的代码部分，以下是翻译的结果：
"A simple debugging shows that the T(:,j)<Tm is always true, hence the else branch never executes."
简单的调试显示T(:,j)<Tm始终为真，因此else分支永远不会执行。
"I've slightly modified your code to add the 'condition_results' matrix that stores the result of the T(:,j)<Tm condition on each iteration of the loop. After the loop, I print the 'condition_results'. Run it and you'll see that each element of this matrix is '1' ('true'). That shows that T(:,j)<Tm is always true (why it's always 'true' is a whole another question, though)."
我稍微修改了你的代码，添加了存储循环每次迭代中T(:,j)<Tm条件结果的'condition_results'矩阵。循环结束后，我打印了'condition_results'。运行代码，你会看到这个矩阵的每个元素都是'1'（'true'）。这表明T(:,j)<Tm始终为真（为什么它总是为真是另一个问题，不过）。
"Hope that helps. Here's the modified code:"
希望这有所帮助。以下是修改后的代码：
英文:
A simple debugging shows that the T(:,j)<Tm is always true, hence the else branch never executes.
I've slightly modified your code to add the 'condition_results' matrix that stores result of the T(:,j)<Tm condition on each iteration of the loop. After the loop I print the 'condition_results'. Run it and you'll see that each element of this matrix is '1' ('true'). That shows that T(:,j)<Tm is always true (why it's always 'true' is a whole another question, though).
Hope that helps. Here's the modified code:
clc
clear all
rho = 0.9;
k = 0.0018;
cp = 1.92;
l = 0.1525;
layers = 10;
dx = l/layers;
z = l-(dx/2): - dx: dx/2;
time = 25;
dt = 1;
t = 1: dt: time;
T0 = 25;
Tm1 = 165;
Tm2 = 135;
X01 = 0.25;
X02 = 0.3;
F0 = 2.202;
F = zeros(1,length(t));
T = zeros(length(z), length(t));
n = 1;
modulatingcycles = 4;
Tm = Tm1*ones(length(z),1);
for i = 1:round(length(z)*X01/(X01+X02))
ind1 = randi([1 length(z)],1,1);
Tm(ind1) = Tm2;
end
condition_results = [];
for j = 1 : length(t)
result = T(:,j)<Tm
condition_results = [condition_results result];
if T(:,j)<Tm
%sum(T(:,j)<Tm)==layers
F(j) = F0;
n = n + 1;
else
x = ceil((length(t) - n)/modulatingcycles);
y = n;
F(y:y+x) = F0/2;
F(y+x+1:y+x+x) = F0;
if j == y + x + x
y = y + x + x + 1;
end
end
for i = 1 : length(z)
T(i,j) = T (i,j) + T0 + ((F(j)*t(j))/(rho*cp*l)) + ((F(j)*l/k) * (3*(z(i)^2) - (l^2)) / (6*l^2));
end
end
disp(condition_results);
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