Struct SBGraph creation from model JSON input.

[joaquinffernandez]

model rltest
  constant Integer N=10;
  Real x1[N];
  Real X2[1];
  Real a1[N];
  parameter Real R=1,C=1,L=1;
equation
  a1[1]=((10-x1[1])^3)/R;
  for i in 1:N-1 loop
    a1[i+1]=((x1[i]-x1[i+1])^3)/R;
  end for;
  for i in 1:N-1 loop
    der(x1[i])=((a1[i]-a1[i+1])^3)/C;
  end for;
  der(x1[N])=(a1[N]-x2[1])/C;
  der(x2[1])=x1[N]/L;
  ...
end rltest;

The JSON format is quite similar to the one defined here. From the variable definitions of the model, we define the following nodes:

  Real x1[N]; // Node 1, state variable.
  Real X2[1]; // Node 2, state variable.
  Real a1[N]; // Node 3, algebraic variable.

$V_1 = \{$
$\text{id} : X1$
$\text{type} = State$
$\}$

$N_1 = \{$
$\text{id} : n_1$
$\text{interval} : [1,N]$
$\text{lhs} : \{V_1\}$
$\text{rhs} : \{\}$
$\}$

$V_2 = \{$
$\text{id} : X2$
$\text{type} = State$
$\}$

$N_2 = \{$
$\text{id} : n_2$
$\text{interval} : [1,1]$
$\text{lhs} : \{V_2\}$
$\text{rhs} : \{\}$
$\}$

$V_3 = \{$
$\text{id} : a$
$\text{type} = Algebraic$
$\}$

$N_3 = \{$
$\text{id} : n_3$
$\text{interval} : [1,N]$
$\text{lhs} : \{V_3\}$
$\text{rhs} : \{\}$
$\}$

Then from the equations of the model, we can define:

• From a1[1]=((10-x1[1])^3)/R; :

  $V_4 = \{$
  $\text{id} : a1$
  $\text{exp} = (0,1) \rightarrow$ to form the expression that corresponds to $a1[1]$
  $\}$

  $V_5 = \{$
  $\text{id} : X1$
  $\text{exp} = (0,1) \rightarrow$ to form the expression that corresponds to $X1[1]$
  $\}$

  $N_4 = \{$
  $\text{id} : n_4$
  $\text{interval} : [1,1]$
  $\text{lhs} : \{V_{4}\}$
  $\text{rhs} : \{V_{5}\}$
  $\}$

• From:

  for i in 1:N-1 loop
      a1[i+1]=((x1[i]-x1[i+1])^3)/R;
  end for;
  

  $V_6 = \{$
  $\text{id} : a1$
  $\text{exp} = (1,1) \rightarrow$ to form the expression $1\times i+1$ that corresponds to $a1[i+1]$
  $\}$

  $V_7 = \{$
  $\text{id} : X1$
  $\text{exp} = (1,0) \rightarrow$ to form the expression $1\times i+0$ that corresponds to $X1[i]$
  $\}$

  $V_8 = \{$
  $\text{id} : X1$
  $\text{exp} = (1,1) \rightarrow$ to form the expression $1\times i+1$ that corresponds to $X1[i+1]$
  $\}$

  $N_5 = \{$
  $\text{id} : n_5$
  $\text{interval} : [1,N-1]$
  $\text{lhs} : \{V_{6}\}$
  $\text{rhs} : \{V_{7},V_{8}\}$
  $\}$

• From:

  for i in 1:N-1 loop
     der(x1[i])=((a1[i]-a1[i+1])^3)/C;
  end for;
  

  $V_9 = \{$
  $\text{id} : X1$
  $\text{exp} = (1,0) \rightarrow$ to form the expression $1\times i+0$ that corresponds to $a1[i]$
  $\}$

  $V_10 = \{$
  $\text{id} : a1$
  $\text{exp} = (1,0) \rightarrow$ to form the expression $1\times i+0$ that corresponds to $a1[i]$
  $\}$

  $V_11 = \{$
  $\text{id} : a1$
  $\text{exp} = (1,1) \rightarrow$ to form the expression $1\times i+1$ that corresponds to $a1[i+1]$
  $\}$

  $N_6 = \{$
  $\text{id} : n_6$
  $\text{interval} : [1,N-1]$
  $\text{lhs} : \{V_{9}\}$
  $\text{rhs} : \{V_{10},V_{11}\}$
  $\}$

• From der(x1[N])=(a1[N]-x2[1])/C; :

  $V_12 = \{$
  $\text{id} : X1$
  $\text{exp} = (0,N) \rightarrow$ to form the expression $0\times i+N$ that corresponds to $X1[N]$
  $\}$

  $V_13 = \{$
  $\text{id} : a1$
  $\text{exp} = (0,N) \rightarrow$ to form the expression $0\times i+N$ that corresponds to $a1[N]$
  $\}$

  $V_14 = \{$
  $\text{id} : X2$
  $\text{exp} = (0,1) \rightarrow$ to form the expression $1\times 0+1$ that corresponds to $X2[1]$
  $\}$

  $N_7 = \{$
  $\text{id} : n_7$
  $\text{interval} : [1,1]$
  $\text{lhs} : \{V_{12}\}$
  $\text{rhs} : \{V_{13},V_{14}\}$
  $\}$

• Finally, from der(x2[1])=x1[N]/L; :

  $V_15 = \{$
  $\text{id} : X1$
  $\text{exp} = (0,1) \rightarrow$ to form the expression $0\times i+1$ that corresponds to $X2[1]$
  $\}$

  $V_16 = \{$
  $\text{id} : X1$
  $\text{exp} = (0,N) \rightarrow$ to form the expression $0\times i+N$ that corresponds to $X1[N]$
  $\}$

  $N_8 = \{$
  $\text{id} : n_8$
  $\text{interval} : [1,1]$
  $\text{lhs} : \{V_{15}\}$
  $\text{rhs} : \{V_{16}\}$
  $\}$

An the final definition is:

$Nodes = \{N_1, N_2,N_3, N_4, N_5, N_6, N_7, N_8\}$