How to write conditional statement/loop?

I need to plot with an expression for V<0 and another expression for V>0.
clc
clear all
n = 1.02; %Ideality factor
A = 33.65; %Richardson constant
q = 1.602*10^-19; % electron charge
K = 1.38*10^-23; %Boltzmann constant
T = 300; % Absolute temperature
phi_b = 0.28; %Barrier Height
J_0 = A* (T* T)* exp((-q* phi_b)./(K* T));
V = linspace(0,2);
if V<0
J = -J_0;
else
J = J_0.* exp((q* V)./(n* K* T)).* (1 - (exp(-q* V)./(K* T)));
end
plot(V, log(J ./(1 - exp(-q* V)/(K *T))));

 采纳的回答

For V = linspace(0, 2) there is no V < 0. But in general:
V = linspace(-2, 2);
J = J_0.* exp((q * V) ./ (n * K * T)) .* (1 - (exp(-q * V) ./ (K * T)));
J(V < 0) = -J_0;

2 个评论

So, a If Else statement doesn't work here?
Of course it would work, but it is slower, less elegant and offers more chances for typos:
V = linspace(-2, 2, 100);
J = NaN(size(V)); % Pre-allocation
for k = 1:numel(V)
if V(k) < 0
J(k) = -J_0;
else
J(k) = J_0 * exp((q * V(k)) / (n * K * T)) * (1 - (exp(-q * V(k)) / (K * T)));
end
end
% Or slightly simpler:
V = linspace(-2, 2, 100);
J = repmat(-J_0, size(V)); % Pre-allocation with default value
for k = 1:numel(V)
if V(k) >= 0
J(k) = J_0 * exp((q * V(k)) / (n * K * T)) * (1 - (exp(-q * V(k)) / (K * T)));
end
end

请先登录,再进行评论。

更多回答(0 个)

类别

帮助中心File Exchange 中查找有关 Mathematics 的更多信息

产品

版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by