Unrecognized function or variable 'ramp'

% example $Signal Generation = y(t)=3r(t+3)-6r(t+1)+3r(t)-3u(t-3) %
clear all; clf;
Ts=0.01; t=-5:Ts:5 ; %Support of signal
%Ramp with support
y1=ramp(t,3,3); %slope of 3 and advanced by 3
y2=ramp(t,-6,1); %slope of -6 and advanced by 1
y3=ramp(t,3); %slope of 3 
%unit step with support [-5,5]
y4=-3*unitstep(t,-3); %amplitude of -3 and delayed by -3
y=y1+y2+y3+y4;
plot(t,y);

%please tell me how to correct this

[Gwinyai Munanairi]

The line that says y3 = ramp(t,3) should be: y3 = ramp(t,3,0) because the ramp() function needs all three parameters, it won't run with 2 parameters. skrrrrr!

Answer 1

[Walter Roberson]

ramp() is defined only by Simulink Test toolbox https://www.mathworks.com/help/sltest/ref/ramp.html

There is also a Simulink Ramp block; https://www.mathworks.com/help/simulink/slref/ramp.html

The example at https://www.mathworks.com/help/signal/gs/impulse-step-and-ramp-functions.html shows how to create a simple ramp function:

ramp = @(t) t.*(t>=0);

Presumably your course provided you with a ramp function such as

ramp = @(t,slope,advanced) @(t) slope.*(t-advanced).*(t>=advanced)

but I could be confusing the meaning of advanced. And this function would have to be improved a bit to take into account that the advancement parameter is optional. Perhaps you are expected to code the function?