Anonymous function or for loop?
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Assume I have a simple electrical function of V=C*sin(t) where C is a constant which varies based on t intervals.
I have used 2 methods to generate the C and by using tic/toc to check, Method 2 seems to be faster than Method 1.
For efficiency and speed wise, should I always use anonymous function instead of for loop? Or is my loop not being coded efficient enough?
t = 0 : 0.1 : 20;
c1 = 53; % (0 <= t <= 10)
c2 = 68; % (10 < t <= 20)
% Method 1 (For Loop)
tic
n = length(t);
a = ones(1,n);
for i = 1:n
if t(i)>=0 && t(i)<=10
A = c1;
else
A = c2;
end
a(i) = A;
end
toc
% Method 2 (Anonymous Function)
tic
C = @(t) (t>=0 & t<=10).*c1 + (t>10).*c2;
c = C(t);
toc
v = sin(t);
v2 = c.*v;
v3 = a.*v;
% Checking
a==c;
v2==v3;
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采纳的回答
KSSV
2021-6-24
Off course, you can achieve the same without using anonymous function.
t = 0 : 0.1 : 20;
c1 = 53; % (0 <= t <= 10)
c2 = 68; % (10 < t <= 20)
tic
a = c1*ones(size(t)) ;
a(t>10) = c2 ;
toc
% Method 2 (Anonymous Function)
tic
C = @(t) (t>=0 & t<=10).*c1 + (t>10).*c2;
c = C(t);
toc
v = sin(t);
v3 = a.*v;
v4 = a.*v ;
% Checking
isequal(a,c)
isequal(v3,v4)
更多回答(2 个)
Sulaymon Eshkabilov
2021-6-24
Your second method is much faster. Try to avoid for or while loop if feasible.
At the same time, you may improve your 2nd method by computing the values of C directly for the predefined values of t, e.g:
% Method 2 (Anonymous Function)
t1 =0:0.1:10; t2 =10.01:.1:20; % t is split up into two ranges
tic
C =t1*c1 + t2*c2;
toc
v = sin(t);
v2 = C.*v;
v3 = a.*v;
% Checking
a==c;
v2==v3;
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