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Cubic Bezier Control Point Sensitivity Tool

Calculate cubic bezier control point sensitivity from explicit caller-supplied inputs.

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Description

For parameter t in [0, 1], choose the cubic Bernstein weight (1-t)³, 3(1-t)²t, 3(1-t)t², or t³ for control 0-3.

Bernstein basis weights describe how Bézier control points contribute to a curve at a normalized parameter. Endpoint weights and interior sensitivities are different evaluations of the same basis.

For parameter t in [0, 1], choose the cubic Bernstein weight (1-t)³, 3(1-t)²t, 3(1-t)t², or t³ for control 0-3.

When to use this tool

Use Cubic Bezier Control Point Sensitivity when you need one Bernstein or control-point weight.

How to use the tool and how it works

  1. Enter parameter, control. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read weight. Use the output convention below.

For parameter t in [0, 1], choose the cubic Bernstein weight (1-t)³, 3(1-t)²t, 3(1-t)t², or t³ for control 0-3.1

Input fieldMeaning and unitsAccepted input
parameterNormalized interpolation coordinate under the stated domain; may permit extrapolation.Required. Finite number; minimum 0; maximum 1.
controlControlRequired. Safe integer; minimum 0; maximum 3.
Output fieldInterpretationReturned shape
weightWeightRequired. Finite number.
json
{
  "input": {
    "parameter": 0.5,
    "control": 1
  },
  "output": {
    "weight": 0.375
  }
}

Limitations and assumptions

  • This is one control-point sensitivity, not a complete curve, tangent, or control-point fit.
  • Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
  • Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use all basis weights and aligned control coordinates to evaluate a complete curve or its derivatives.

References

  1. Calculation and input contract: interpolation/cubic-bezier-control-point-sensitivity — tool.io

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