### What different options do I have to initialise a DSL model?

Category:
Dynamic Simulation

There are several possibilities to calculate the initial conditions. Consider the example y=a*u+b, where y is the output and u the input signal of the model. The initial value of y is known (=0), normally determined from outside, if the output is not connected then it will be determined in the model itself (inc0). The initial value of u is unknown.

- Approach 1, analytical solution (direct input of initial value, not possible in the example above):
y=2+3*u
inc0(y)=5
inc(u)=(y‐2)/3

- Approach 2, loopinc (simple linear search for initial value):
y=2+3*u
inc0(y)=5
inc(u) = loopinc(y, ‐10, 10, 0.01, 0.001)

- Approach 3, intervalinc ('interval‐division search' for initial value):
y=2+3*u
inc0(y)=5
inc(u) = intervalinc(y, ‐10, 10, 40, 0.001)

- Approach 4, newtoninc (newton iterative search for initial value normally using a set of coupled
equations):
y=2+3*u
inc0(y)=5
inc(u) = newtoninc((y‐2)/3, 0, 100, 0.001)

- Approach 5, automatic calculation of initial conditions (option in block definition must be set):
y=2+3*u
inc0(y)=5
inc(u) = 0 ! initial value for automatic calculation

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