Another issue. How to pass parameters and in the same time specify initial conditions.

[mph-]

Another issue. How to pass parameters and in the same time specify initial conditions. For example with the syntax below the simulation is erroneous.

from lcapy import Circuit
import numpy as np
import matplotlib.pyplot as plt

##cct = Circuit('''
##... Vin 1 0 {sin(130e6*2*3.14159*t)}
##... Rin 1 2 50
##... Cs  2 4 2.34e-12 0
##... La  2 3 0.32e-6 0
##... Rs  3 4 0.532
##... Rl  4 0 50''')

cct = Circuit('''
... Vin 1 0 {sin(130e6*2*3.14159*t)}
... Rin 1 2
... Cs  2 4 0
... La  2 3 0
... Rs  3 4
... Rl  4 0''')

cct1 = cct.subs({'Rin': 50, 'Cs':2.34e-12, 'La': 0.32e-6, 'Rs': 0.532, 'Rl': 50})
##H = cct.transfer(1,0,4,0)
##print(H)

t = np.linspace(0, 2e-7, 1000)
Vinp = cct1.Vin.v.evaluate(t)
Vout = cct1.Rl.v.evaluate(t)

plt.plot(t, Vinp, 'g', linewidth=2)
plt.plot(t, Vout, 'r', linewidth=2)
plt.grid(b=True, which='major', color='#666666', linestyle='-')
plt.minorticks_on()
plt.grid(b=True, which='minor', color='#999999', linestyle='-', alpha=0.2)
plt.show()

Originally posted by @SanchoPansa47 in https://github.com/mph-/lcapy/issues/35#issuecomment-721104952

[mph-]

This is notation problem. The first netlist specifies transient analysis; the second specifies phasor analysis.

In the first netlist you specify the initial current for the inductor and the initial voltage for a capacitor, thus, Lcapy solves the circuit as an initial value problem:

`>>> cct = Circuit("""
 Vin 1 0 {sin(130e6*2*3.14159*t)}
 Rin 1 2 50
 Cs  2 4 2.34e-12 0
 La  2 3 0.32e-6 0
 Rs  3 4 0.532
 Rl  4 0 50""")

 >>> cct.describe()
This has initial conditions so is an initial value problem solved in the s-domain using Laplace transforms.

>>> cct.analysis                                                            
{'zeroic': True,
'has_ic': True,
'ivp': True,
'has_dc': False,
'has_ac': False,
'has_s': False,
'has_transient': True,
'reactances': ['Cs', 'La'],
'dependent_sources': [],
'independent_sources': ['Vin'],
'control_sources': [],
'ac': False,
'dc': False,
'causal': False,
'time_domain': False}`

For the second netlist, no initial conditions are specified:

`>>> cct = Circuit('''
Vin 1 0 {sin(130e6*2*3.14159*t)}
Rin 1 2
Cs  2 4 0
La  2 3 0
Rs  3 4
Rl  4 0''')

>>> cct.describe()                                                         
Phasor analysis is used for source Vin.

{'zeroic': True,
'has_ic': False,
'ivp': False,
'has_dc': False,
'has_ac': False,
'has_s': False,
'has_transient': True,
'reactances': ['Cs', 'La'],
'dependent_sources': [],
'independent_sources': ['Vin'],
'control_sources': [],
'ac': False,
'dc': False,
'causal': False,
'time_domain': False}`

I would appreciate any suggestions of how to clarify or make it more intuitive.

Michael.

[SanchoPansa47]

Didn't understand. Is there a way to describe a circuit using parameters (i.e. Cs, La, etc.) and in the same time apply initial conditions for C and L. Then substitute the parameters with real values using subs. What would be the syntax for such scenario ?

[mph-]

`>>> cct = Circuit("""
 Vin 1 0 {sin(130e6*2*3.14159*t)}
 Rin 1 2 50
 Cs  2 4 2.34e-12 v0
 La  2 3 0.32e-6 i0
 Rs  3 4 0.532
 Rl  4 0 50""")

 >>> cct2 = cct.subs({'i0':1, 'v0':2})
 >>> cct2.La.V(t)
 # or
 >>> cct.La.V(t).subs({'i0':1, 'v0':2})`

[SanchoPansa47]

In your example you specified components values as constants and initial conditions as symbols. I search for inverse solution: component values - symbols, initial values - constants. Possible ?

[mph-]

Sorry, I don't fully understand your question.

You can define a capacitor with capacitance C and initial voltage v0 as C1 1 2 C v0

If you know the initial value, say 0.1 V, you can either substitute the symbolic value or define the capacitor as

C1 1 2 C 0.1

MIchael.

[SanchoPansa47]

Works. Thanks !