5.1.6.3. Usecase: Reset at initial point

Description: This example shows that reset evaluation can happen throughout the simulation, including at the very beginning.

Note that:

• all elements are in the same component;

• the order values of resets are not shown;

• all variables have dimensionless units;

• the initial conditions hold when t = 0.

component:
  ├─ math:
  │    └─ x = t % 1000
  │
  ├─ variable: x
  │
  └─ variable: y, initially 0
      ├─ reset: rule 1
      │   ├─ when x == 0
      │   └─ then y = 1
      │
      └─ reset: rule 2
          ├─ when x == 1
          └─ then y = 0

See CellML syntax

<variable name="t" units="dimensionless" />
<variable name="x" units="dimensionless" />
<variable name="y" units="dimensionless" initial_value="0" />

<!-- Reset rule 1: -->
<reset variable="y" test_variable="x">
    <test_value>
        <cn units="cellml:dimensionless">0</cn>
    </test_value>
    <reset_value>
        <cn units="cellml:dimensionless">1</cn>
    </reset_value>
</reset>

<!-- Reset rule 2: -->
<reset variable="y" test_variable="x">
    <test_value>
        <cn units="cellml:dimensionless">1</cn>
    </test_value>
    <reset_value>
        <cn units="cellml:dimensionless">0</cn>
    </reset_value>
</reset>

Processing steps

t	0.0	0.1	…
x	0	0.1	…
y	0 → 1	1	…

• Cycle 1

  1. At t = 0 we detect that x == 0, so rule 1 becomes active.

  2. The reset value for rule 1 is calculated to be 1.

  3. The reset value for rule 1 is applied to y.

  4. The system is now in a new state: \((x^\prime, t, p) \neq (x, t, p)\), we restart at step 1.

• Cycle 2

  1. Since it is still true that x == 0, rule 1 is still active.

  2. The reset value for rule 1 is (again) calculated to be 1.

  3. The reset value for rule 1 is (again) applied to y.

  4. The state hasn’t changed: \((x^\prime, t, p) == (x, t, p)\), so reset rule 1 processing halts.

• Cycle 3

  1. No other resets are found to be active, so the reset evaluation cycles finish and model dynamics continue.

t	0.0	0.1	…	0.9	1.0	1.1	…
x	0	0.1	…	0.9	1.0	1.1	…
y	0 → 1	1	…	1	1 → 0	0	…

• Cycle 4

  1. At t = 1 we detect that x == 1, so rule 2 becomes active.

  2. The reset value for rule 2 is calculated to be 0.

  3. The reset value for rule 2 is applied to y.

  4. The system is now in a new state: \((x^\prime, t, p) \neq (x, t, p)\), so restart.

• Cycle 5

  1. Since it is still true that x == 1, rule 2 is still active.

  2. The reset value for rule 2 is calculated (still) to be 0.

  3. And reset value for rule 2 is applied to y.

  4. The state hasn’t changed: \((x^\prime, t, p) == (x, t, p)\), so reset rule 2 processing halts.

• Cycle 6

  1. No other resets are found to be active, so the reset evaluation cycles finish and model dynamics continue.