how to vectorize this "For Loop" ?

조회 수: 1 (최근 30일)
nelson
nelson 2017년 7월 16일
답변: Walter Roberson 2017년 7월 16일
close all
clear all
clc
tic;
for k=1:0.5:10;
for a=1:0.5:5;
num=k;
den=[1 a 0];
sys=tf(num,den);
bode(sys);grid on;hold on;
end
end
time=toc

채택된 답변

Walter Roberson
Walter Roberson 2017년 7월 16일
k=1:0.5:10;
a=1:0.5:5;
[K, A] = ndgrid(k, a);
Numerator = num2cell(K(:));
nusz = size(Numerator);
Denominator = num2cell( [ones(nusz), A(:), zeros(nusz)], 2);
tfs = tf(Numerator, Denominator);
Now at this point you have two choices:
1)
bode(tfs); grid on
This is not the same as your original code: it produces an array of plots. To be honest, it is not understandable even in full screen mode -- it just looks like a series of straight lines across the screen. However, the execution time is not so bad considering.
2)
for K = 1 : 171; bode(tfs(K)); hold on; end; grid on
This is the same as your original code. It would create a single pair of plots with 171 lines each (but most of which overlay each other.) This takes quite a while to execute.
The drawing of the plots takes much much longer than the creation of the transfer functions -- to the point where it is hardly even worth bothering to vectorize the creation of the transfer functions considering the loss in clarity about what is being plotted.

추가 답변 (1개)

scadaprog
scadaprog 2017년 7월 16일
Hi, This is one way of doing it:
k=1:.5:10; a=1:.5:5;
num=repmat(k',numel(a),1);
a = [ones(numel(a),1) a' zeros(numel(a),1)];
den = repmat(a, numel(k),1);
sys = tf(num2cell(num),num2cell(den,2));
bode(sys);

카테고리

Help CenterFile Exchange에서 Time and Frequency Domain Analysis에 대해 자세히 알아보기

제품

Community Treasure Hunt

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

Start Hunting!

Translated by