11.8: Example- Evaluating an Expression

Now let us build a model for a slightly more interesting expression:

2X + 3Y

If X = 10 and Y = 20, the result should be:

2(10) + 3(20) = 20 + 60 = 80

Blocks needed:

• Two Constant blocks
• Two Gain blocks
• One Sum block
• One Display block

A Gain block multiplies an input by a constant value. In this example, one Gain block multiplies X by 2 and the other Gain block multiplies Y by 3.

Build the model using these steps:

1. Define X and Y in MATLAB or in the model initialization callback.

2. Use one Constant block for X and one Constant block for Y.

3. Connect X to a Gain block with gain value 2.

4. Connect Y to a Gain block with gain value 3.

5. Connect both Gain block outputs to a Sum block.

6. Connect the Sum block to a Display block.

7. Run the model.

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