why am I getting the error "Incorrect number or types of inputs or outputs for function 'step."

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민준 김
민준 김 2023-9-22
评论： Jon 2023-9-22
my code is
clear all, close all
m1 = 10;
m2 = 350;
kw = 500000;
ks = 10000;
B = [ 1000 2000 3000 4000 ];
t = 0:0.01:2;
for i = 1:4
b = B(i);
F = [ 0 1 0 0; -( ks/m1 + kw/m1 ) -b/m1 ks/m1 b/m1; 0 0 0 1; ks/m2 b/m2 -ks/m2 -b/m2 ];
G = [ 0; kw/m1; 0; 0 ];
H = [ 1 0 0 0; 0 0 1 0 ];
J = 0;
y = step( F, G, H, J, 1, t );
subplot(2,2,i);
plot(t, y(:,1), ':', t, y(:,2), '-' );
legend('Wheel','Car');
ttl= sprintf('Response with b = %4.1f',b);
title(ttl);
end
and i got
"Incorrect number or types of inputs or outputs for function 'step'."
this message
  3 个评论
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Mathieu NOE
Mathieu NOE 2023-9-22
this is ok for older matlab releases
if you use a recent matlab version, please create first the system sys and them call step(sys) as described in the doc :
Step response of dynamic system - MATLAB step - MathWorks France
FYI , in ttachment the "old" step function if you need it

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回答（1 个）

Jon
Jon 2023-9-22
Ran in:
This runs for me in R2023b, what version are you running? If I look at the actual step.m file in my directory, which comes up as C:\Program Files\MATLAB\R2023a\toolbox\control\ctrlobsolete\step.m
I see that the calling arguments that you use will no longer be supported. Instead you must make a linear system and pass this to test. Perhaps on your version the call using A,B,C,D matrices is already no longer supported.
% Old help
%warning(['This calling syntax for ' mfilename ' will not be supported in the future.'])
%STEP Step response of continuous-time linear systems.
% STEP(A,B,C,D,IU) plots the time response of the linear system:
% .
% x = Ax + Bu
% y = Cx + Du
m1 = 10;
m2 = 350;
kw = 500000;
ks = 10000;
B = [ 1000 2000 3000 4000 ];
t = 0:0.01:2;
for i = 1:4
b = B(i);
F = [ 0 1 0 0; -( ks/m1 + kw/m1 ) -b/m1 ks/m1 b/m1; 0 0 0 1; ks/m2 b/m2 -ks/m2 -b/m2 ];
G = [ 0; kw/m1; 0; 0 ];
H = [ 1 0 0 0; 0 0 1 0 ];
J = 0;
y = step( F, G, H, J, 1, t );
subplot(2,2,i);
plot(t, y(:,1), ':', t, y(:,2), '-' );
legend('Wheel','Car');
ttl= sprintf('Response with b = %4.1f',b);
title(ttl);
end
In any case I would recommend calling using the current version of step, which is
figure % make new figure
m1 = 10;
m2 = 350;
kw = 500000;
ks = 10000;
B = [ 1000 2000 3000 4000 ];
t = 0:0.01:2;
for i = 1:4
b = B(i);
F = [ 0 1 0 0; -( ks/m1 + kw/m1 ) -b/m1 ks/m1 b/m1; 0 0 0 1; ks/m2 b/m2 -ks/m2 -b/m2 ];
G = [ 0; kw/m1; 0; 0 ];
H = [ 1 0 0 0; 0 0 1 0 ];
J = 0;
sys = ss(F,G,H,J);
y = step( sys,t );
subplot(2,2,i);
plot(t, y(:,1), ':', t, y(:,2), '-' );
legend('Wheel','Car');
ttl= sprintf('Response with b = %4.1f',b);
title(ttl);
end

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