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inverse updates work for parabola with vertex and point #259

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merged 2 commits into from
Nov 22, 2024
Merged

inverse updates work for parabola with vertex and point #259

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e7dd845
inverse updates work for parabola with vertex and point
dqnykamp Nov 22, 2024
761c6d5
delete converted parabola tests
dqnykamp Nov 22, 2024
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143 changes: 133 additions & 10 deletions packages/doenetml-worker/src/components/Parabola.js
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Original file line number Diff line number Diff line change
Expand Up @@ -477,6 +477,28 @@ export default class Parabola extends Curve {

return { setValue: { numericalPrescribedVertex: [x, y] } };
},

inverseDefinition({
desiredStateVariableValues,
dependencyValues,
}) {
if (dependencyValues.prescribedVertex === null) {
return { success: false };
}

return {
success: true,
instructions: [
{
setDependency: "prescribedVertex",
desiredValue: me.fromAst([
"vector",
...desiredStateVariableValues.numericalPrescribedVertex,
]),
},
],
};
},
};

stateVariableDefinitions.pointsAreNumerical = {
Expand Down Expand Up @@ -597,13 +619,16 @@ export default class Parabola extends Curve {
realValued: true,
},
};
} else {
// vertex and at least one point prescribed.
// use the first point and ignore the remaining
} else if (
dependencyValues.numericalThroughPoints.length === 1
) {
// vertex and one point prescribed.

// create parabola y = a*(x-x1)^2 + y1
// where a is determined by the first point

// if point is on top of vertex, then ignore it

let v = dependencyValues.numericalPrescribedVertex;
let x1 = v[0];
let y1 = v[1];
Expand All @@ -612,17 +637,38 @@ export default class Parabola extends Curve {
let x2 = p1[0];
let y2 = p1[1];

a = (y2 - y1) / (x2 - x1) ** 2;
b = -2 * a * x1;
c = a * x1 * x1 + y1;
if (x1 === x2) {
if (y1 == y2) {
a = dependencyValues.aShadow;
b = -2 * a * x1;
c = a * x1 ** 2 + y1;
} else {
realValued = false;
a = NaN;
b = NaN;
c = NaN;
}
} else {
a = (y2 - y1) / (x2 - x1) ** 2;
b = -2 * a * x1;
c = a * x1 * x1 + y1;
}

return { setValue: { a, b, c, realValued } };
} else {
let warning = {
message:
"Haven't implemented parabola with vertex through more than 1 point.",
level: 1,
};
return {
setValue: {
a,
b,
c,
realValued: true,
a: NaN,
b: NaN,
c: NaN,
realValued: false,
},
sendWarnings: [warning],
};
}
}
Expand Down Expand Up @@ -876,6 +922,83 @@ export default class Parabola extends Curve {
}
};

if (dependencyValues.numericalPrescribedVertex) {
if (dependencyValues.numericalThroughPoints.length === 0) {
// just vertex
// move it to be at vertex with new parameter values
// modify a if changed

let a = await getWorkingParameterValue("a");
let b = await getWorkingParameterValue("b");
let c = await getWorkingParameterValue("c");

let x1 = -b / (2 * a);
let y1 = c - (b * b) / (4 * a);

let instructions = [
{
setDependency: "numericalPrescribedVertex",
desiredValue: [x1, y1],
},
];

if (desiredNumericalValues.a !== undefined) {
instructions.push({
setDependency: "aShadow",
desiredValue: desiredNumericalValues.a,
});
}

return {
success: true,
instructions,
};
} else {
// vertex and one point prescribed

// Move vertex to be at the new vertex.
// Translate the point horizontally by the amount vertex moved
// and move point vertical to parabola

let a = await getWorkingParameterValue("a");
let b = await getWorkingParameterValue("b");
let c = await getWorkingParameterValue("c");

let vx = -b / (2 * a);
let vy = c - (b * b) / (4 * a);

let dx =
vx - dependencyValues.numericalPrescribedVertex[0];

let px =
dependencyValues.numericalThroughPoints[0][0] + dx;
let py = a * px * px + b * px + c;

let instructions = [
{
setDependency: "numericalPrescribedVertex",
desiredValue: [vx, vy],
},
{
setDependency: "numericalThroughPoints",
desiredValue: [[px, py]],
},
];

if (desiredNumericalValues.a !== undefined) {
instructions.push({
setDependency: "aShadow",
desiredValue: desiredNumericalValues.a,
});
}

return {
success: true,
instructions,
};
}
}

if (dependencyValues.numericalThroughPoints.length === 0) {
let instructions = [];

Expand Down
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