Add

block Add "Output the sum of the two inputs"
    extends Interfaces.SI2SO;

    parameter Real k1 = 1 "Gain of input signal 1";
    parameter Real k2 = 1 "Gain of input signal 2";
equation
    y = k1 * u1 + k2 * u2;

    annotation (
        Documentation(info = "<html>\n<p>\nThis blocks computes output <strong>y</strong> as <em>sum</em> of the\ntwo input signals <strong>u1</strong> and <strong>u2</strong>:\n</p>\n<pre>\n    <strong>y</strong> = k1*<strong>u1</strong> + k2*<strong>u2</strong>;\n</pre>\n<p>\nExample:\n</p>\n<pre>\n     parameter:   k1= +2, k2= -3\n\n  results in the following equations:\n\n     y = 2 * u1 - 3 * u2\n</pre>\n\n</html>"),
        Icon(
            coordinateSystem(
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                extent = {
                    {-100, -100}, 
                    {100, 100}}),
            graphics = {
                Line(
                    points = {
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                    color = {0, 0, 127}), 
                Line(
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                    extent = {
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                Line(
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                    color = {0, 0, 127}), 
                Text(
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                    textString = "+"), 
                Text(
                    extent = {
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                        {5, 92}},
                    textString = "%k1"), 
                Text(
                    extent = {
                        {-100, -92}, 
                        {5, -52}},
                    textString = "%k2")}),
        Diagram(
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                extent = {
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            graphics = {
                Rectangle(
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                    textString = "+"), 
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                    textString = "k1"), 
                Text(
                    extent = {
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                    textString = "k2")}));
end Add;