Hello Mahmoud,
I can't see all your code, so I have to assume that all the rest is correct and, that you need to plot the functions "deltaP_AtoB1" and "deltaP_AtoB2" against the variable "V_c", correct ?! Try to rewrite the commands as follow:
Case 1) V_c = linspace(0,1,15)
deltaP_AtoB1 = ...
deltaP_AtoB2 = ...
plot(V_c, deltaP_AtoB1)
hold on
plot(V_c, deltaP_AtoB2)
hold off
===> in that case you need to use dots as you perfectly did because you're operating with vectors but you don't need to define deltaP_AtoB as symbolic variable, unless you need it after.
Case 2) Define V_c as a symbolic variable
deltaP_AtoB1 = ...
deltaP_AtoB2 = ...
fplot(V_c, deltaP_AtoB1)
hold on
fplot(V_c, deltaP_AtoB2)
hold off
xlim([0 15]) % eventually
==> in that case you don't need to use dots
I hope it helps, let me know if it works.
Kind regards,
PGP
