# \[Dyad\] “Cyclic guesses detected” in Dyad from non-ideal RLC
**URL:** https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249
**Category:** Modelling & Simulations
**Tags:** modelingtoolkit, dyad
**Created:** [January 25, 2026, 12:31am UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249 "2026-01-25T00:31:51Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@junmorenodi99](https://discourse.julialang.org/u/junmorenodi99)
#### Post date: [January 25, 2026, 12:31am UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/1 "2026-01-25T00:31:51Z")
Hi everyone,
I’ve been experimenting with **Dyad** using the [**RLC circuit example**](https://help.juliahub.com/dyad/dev/tutorials/creating-components.html) from the documentation, except I made it a bit less ideal by adding:
- **coil series resistance** ( RL )
- **capacitor ESR** (Rc
When I add the capacitor ESR, I get **one warning** and **one error**.
**Warning:**
```julia-auto
┌ Warning: Initialization system is overdetermined. 3 equations for 1 unknowns. Initialization will default to using least squares. `SCCNonlinearProblem` can only be used for initialization of fully determined systems and hence will not be used here. To suppress this warning pass warn_initialize_determined = false. To make this warning into an error, pass fully_determined = true
└
```
**Error:**
```julia-auto
ERROR: Cyclic guesses detected in the system. Symbolic values were found for the following variables/parameters in the map:
Rc₊v(t) => (150RLoad₊v(t)) / RLoad₊R
In order to resolve this, please provide additional numeric guesses so that the chain can be resolved to assign numeric values to each variable.
```
From what I understand, the issue comes from **initialization** : there isn’t enough numeric information at t=0, so the solver can’t resolve the system.
However, when I try to add the problematic variable to the initial conditions, the initialization system becomes “weird” (effectively no unknowns), and the result ends up being 0, with a warning like:
```julia-auto
┌ Warning: Initialization system is overdetermined. 2 equations for 0 unknowns. Initialization will default to using least squares. `SCCNonlinearProblem` can only be used for initialization of fully determined systems and hence will not be used here. To suppress this warning pass warn_initialize_determined = false. To make this warning into an error, pass fully_determined = true
└
```
### Questions
In Julia / ModelingToolkit, you can include “soft constraints” via **guesses** , e.g.:
```julia-auto
prob = ODEProblem(sys; defaults, tspan; guesses = [cvar=> 500.0])
```
Is there an equivalent way to provide **numeric guesses** in **Dyad**?
If not, what’s the recommended approach in Dyad to resolve **cyclic guesses** during initialization?
Thanks a lot!
**Code (minimal example):**
- dyad : (Note: all the other components are the same as in the tutorial.)
```julia-auto
component RLC_non_ideal
RL = Resistor(R=0.1)
Rc = Resistor(R=0.01)
RLoad = Resistor(R=150.0)
capacitor = Capacitor(C=1e-6)
inductor = Inductor(L= 3e-3)
source = StepVoltage()
ground = Ground()
relations
initial inductor.i = 0.0
initial capacitor.v = 0.0
initial Rc.v = 0.0 # added after warning
connect(source.p, inductor.p)
connect(inductor.n, RL.p)
connect(RL.n, capacitor.p, RLoad.p)
connect(Rc.p, capacitor.n, RLoad.p)
connect(RLoad.n, Rc.n, source.n, ground.g)
end
analysis SimBoostModel
extends TransientAnalysis(stop=0.5, abstol=1m, reltol=1m )
model = BoostModel()
end
```
- Julia:
```julia-auto
result = SimBoostModel()
```
---
### Author:  [@asinghvi17](https://discourse.julialang.org/u/asinghvi17)
#### Post date: [January 25, 2026, 1:39am UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/2 "2026-01-25T01:39:21Z")
Hey, to directly address the question there is a `guess` relation in Dyad with the same syntax as `initial`. If it’s not in the docs, will add it on Monday!
---
### Author:  [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)
#### Post date: [January 25, 2026, 6:50am UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/3 "2026-01-25T06:50:23Z")
> [@junmorenodi99](#):
>
> `Warning: Initialization system is overdetermined. 3 equations for 1 unknowns`
The problem here is probably not _lack_ of information, I think it’s the opposite, two initial conditions too much. You can ask MTK for `initial_conditions(model)` and see if there are more specified than expected. Have a look at the dimension of the state after `mtkcompile`, and make sure you have specified the same number of initial conditions. If you do not, you’ll have an under or over determined system and initialization will be a bit harder.
---
### Author:  [@johhell](https://discourse.julialang.org/u/johhell)
#### Post date: [January 25, 2026, 7:58am UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/4 "2026-01-25T07:58:26Z")
> [@junmorenodi99](#):
>
> ```julia-auto
> connect(source.p, inductor.p)
> connect(inductor.n, RL.p)
> connect(RL.n, capacitor.p, RLoad.p) <====
> connect(Rc.p, capacitor.n, RLoad.p) <====
> connect(RLoad.n, Rc.n, source.n, ground.g)
>
> ```
Check the connections: `RLoad.p` is connected with both ends of `capacitor` resulting in a short-circuit.
---
### Author:  [@junmorenodi99](https://discourse.julialang.org/u/junmorenodi99)
#### Post date: [January 25, 2026, 4:11pm UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/5 "2026-01-25T16:11:51Z")
You’re right ! thanks for pointing that out.
It was a copy/paste mistake, but even with the correct configuration I’m still seeing the same issue.
```julia-auto
connect(source.p, inductor.p)
connect(inductor.n, RL.p)
connect(RL.n, capacitor.p, RLoad.p)
connect(Rc.p, capacitor.n)
connect(RLoad.n, Rc.n, source.n, ground.g)
```
Here’s the output I’m getting:
```julia-auto
┌ Warning: Did not converge after `maxiters = 100` substitutions. Either there is a cycle in the rules or `maxiters` needs to be higher.
ERROR: Cyclic guesses detected in the system. Symbolic values were found for the following variables/parameters in the map:
RLoad₊v(t) => 599.96 + 0.01capacitor₊i(t)
In order to resolve this, please provide additional numeric guesses so that the chain can be resolved to assign numeric values to each variable.
```
Although it’s true that the symbolic values detected this time are different.
---
### Author:  [@junmorenodi99](https://discourse.julialang.org/u/junmorenodi99)
#### Post date: [January 25, 2026, 4:24pm UTC](https://discourse.julialang.org/t/dyad-cyclic-guesses-detected-in-dyad-from-non-ideal-rlc/135249/6 "2026-01-25T16:24:23Z")
Thanks everyone for the help!
I tried what @asinghvi17 suggested using the corrected model (thanks again @johhell), and this time it worked 🙂.
Here’s the corrected code, plus the extra **guess** added for the variable mentioned in the Error:
```julia-auto
component BoostModel
RL = Resistor(R=0.1)
Rc = Resistor(R=0.01)
RLoad = Resistor(R=150.0)
capacitor = Capacitor(C=1e-6)
inductor = Inductor(L= 3e-3)
source = StepVoltage()
ground = Ground()
relations
initial inductor.i = 0.0
initial capacitor.v = 0.0
guess capacitor.i = 0.0 # added
connect(source.p, inductor.p)
connect(inductor.n, RL.p)
connect(RL.n, capacitor.p, RLoad.p)
connect(Rc.p, capacitor.n)
connect(RLoad.n, Rc.n, source.n, ground.g)
end
```
@baggepinnen thanks for the recommendation. It’ll be useful later for more complex applications.