[?] Get symbolic solution expressions of Delay Differential Equations?

Questions
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1

Hello all,
The Wolfram documentation suggests to tackle Delay differential equations ( DDE’s ) with NSolve, but I need a symbolic expression of the solution for my current analysis. So, I’m trying to solve using Dsolve. I found a thread

which suggests a way to get symbolic expressions and tried the same for my current problem. But, I didn’t get any favorable output. I have attached the file, any help in this regard will be much appreciated.

Thanks in advance

2

I do not know why there is an error but not using Subscript it works :

 DSolve[{q[t] + omc*q[t] - omc*q[t - 1] + 2*sig*q'[t] + q''[t] == 0, 
 q[t /; t < 0] == 0}, q[t], {t, 0, 2}]

aaa.png

Another Example:

  DSolve[{q[t] + omc*q[t] - omc*q[t - 1] + 2*sig*q'[t] + q''[t] == 0, 
  q[t /; t < 0] == 1}, q[t], {t, 0, 1}]

vvvv.png
vvvv.png1261×257 5.48 KB

Regards Mariusz.