Why do I get "Array indices must be positive integers or logical values" error
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t=0:0.01:4;
h1=t.*cos(2.*pi.*t);
subplot(6,1,1);
plot(t,h1);
title 'p(t)';
grid on;
h2=t.*exp(-2.*t);
subplot(6,1,2);
plot(t,h2);
title 'q(t)';
grid on;
h12=h1+h2;
subplot(6,1,3);
plot(t,h12);
title 's(t)';
grid on;
h3=u(t)-u(t-5);
th=0:0.01:8;
h=conv(h12,h3)*0.01;
subplot(6,1,4);
plot(th,h)
grid on;
legend('h(t)')
title 'overall impulse response'
tx=0:0.01:2;
x=tx.*exp(-2.*tx);
subplot(6,1,5);
plot(tx,x)
grid on;
legend('x(t)')
title 'Input signal'
ty=0:0.01:10;
y=conv(x,h)*0.01;
subplot(6,1,6);
plot(ty,y)
grid on;
legend('y(t)')
title 'System Response'
syms t;
int(y,t,-inf,inf);
回答（1 个）
Dyuman Joshi
2021-4-27
Because you are defining an array using negetive indexes.
> h3=u(t)-u(t-5); %u is undefined in your code
As you have defined t=0:0.01:4, values of t-5 become negetive numbers, which can not be used as indexes to define an array.
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2021-4-27
2021-4-27
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