Undefined function sgn(z)

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Advait Sinha
Advait Sinha 2019-6-19
回答： Abhishek Kumar 2019-6-26
close all;
dt = 0.01;%time step
k=1;
m=1;%initial parameters
u1 =1;
u2 =2;
z = u2-u1;
c = sgn(z);
h = c*z;
v=1;
a=1;
tend=10;
t=0;
i=1
while t < tend-2*dt
vh=v(i)-dt*k*h(i)/ (2*m);
h(i+1)= z(i)+ dt*vh;
a(i+1)= -k*h(i+1)/2;
v(i+1)= vh + dt*a(i+1)/2;
i = i+1;
t = t + dt
end
plot(linspace(0,tend,tend/dt),z);

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回答（1 个）

Abhishek Kumar
Abhishek Kumar 2019-6-26
Hi Advait
There is no function called 'sgn' in matlab. It seems that you wanted to use 'sign' to get the sign of the variable and then make it positive.
you can use to command window to find whether a function exists or not, and if it exists what it does. eg.
>> help sign

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