Since you are doing actual numeric calculations, one option is to use matlabFunction to convert ‘X_Laplace’ from a symbolic function to an anonymous function. This has the advantage of being more efficient, and also allowing NaN or Inf values to exist in the ‘Laplace_Values’ vector.
Try this —
syms t s
x(t) = 3*cos(5*t);
X_Laplace(s) = laplace(x(t))
X_Laplace = matlabFunction(X_Laplace)
% (3*s)/(s^2 + 25)
% Numerator root 0
% Denumerator roots +5i and -5i
N = 300; %Number of points in the plot
Frequencies = zeros(1,300);
Laplace_Values = zeros(1,300);
Current_Frequency = -15;
Increment = 0.1;
for i = 1:1:N
Frequencies(1,i) = Current_Frequency;
if Frequencies(1,i) == -5
Laplace_Values(1,i) = 1;
elseif Frequencies(1,i) == 5
Laplace_Values(1,i) = 1;
else
Laplace_Values(1,i) = abs(X_Laplace(Frequencies(1,i)*1i));
end
Current_Frequency = Current_Frequency+Increment;
end
figure
plot(Frequencies,Laplace_Values)
grid on
EDIT — Corrected typographical errors.
.
