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Widget Core Function

The equation widget is used for doing engineering calculations. It’s the primary calculation engine in Calcs.com templates.

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UI Experience

  • Not interactive for the user
  • Displays the equation used for the calculation
  • Shows the calculated value to the user

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Data Organization and Manipulation

Primary widget for:
  • Mathematical calculations and algebraic expressions
  • Conditional statements and checks
  • Iterations and matrix/vector manipulation
Watch tutorials:

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Equation Structure

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Single Equation

{
  "type": "computed",
  "label": "Area",
  "symbol": "A",
  "units": "mm^2",
  "equation": [
    {
      "result": "width * height",
      "condition": "@default"
    }
  ],
  "referenceId": "area"
}

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Multiple Conditional Equations

{
  "type": "computed",
  "label": "Capacity Factor",
  "symbol": "φ",
  "equation": [
    {
      "result": "0.9",
      "condition": "loadType == 'tension'"
    },
    {
      "result": "0.85",
      "condition": "loadType == 'compression'"
    },
    {
      "result": "0.75",
      "condition": "@default"
    }
  ],
  "referenceId": "phi"
}

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Using @ Shortcuts

Simplify equation building by using ”@” to reference other widgets: 
{
  "equation": [
    {
      "result": "@width * @height",
      "condition": "@default"
    }
  ]
}
The ”@” symbol searches by label, symbol, and reference ID, automatically inserting the correct references.
Watch tutorial: Using @ in equations

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Error Handling

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ThrowError vs Throw

  • throwError: Displays a specific message to the user
  • throw: Shows generic “Unexpected Error” message
{
  "equation": [
    {
      "result": "width / height",
      "condition": "height != 0"
    },
    {
      "result": "throwError('Height cannot be zero')",
      "condition": "@default"
    }
  ]
}

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Special “members” Equation Widget

For exporting data to Member Schedule: 
{
  "type": "computed",
  "label": "Members Export",
  "export": true,
  "hidden": true,
  "equation": [
    {
      "condition": "@default",
      "result": "[
        { 
          id: 'member',
          designation: designation,
          length: L,
          lengthUnit: 'm',
          nCom: N_compression,
          comments: 'Main beam'
        }
      ]"
    }
  ],
  "referenceId": "members"
}

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Advanced Features

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Matrix Operations

{
  "result": "[[1,2,3], [4,5,6]] * transpose([[7], [8], [9]])"
}

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Iterations

{
  "result": "sum(iterate(1, 10, 1, i^2, i))"
}

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Unit Conversions

{
  "result": "convert(length, 'mm', 'm')"
}

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Conditional Logic

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Using @default

The @default condition acts as an “else” statement: 
{
  "equation": [
    {
      "result": "value1",
      "condition": "type == 'A'"
    },
    {
      "result": "value2",
      "condition": "type == 'B'"
    },
    {
      "result": "value3",
      "condition": "@default"
    }
  ]
}
Watch tutorial: Using @default

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Best Practices

  • Use meaningful variable names
  • Add comments in authorNotes for complex calculations
  • Include proper error handling
  • Reference relevant standards in the references field
  • Use @default for catch-all conditions
  • Test edge cases thoroughly

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Common Patterns

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Safety Factor Application

{
  "result": "phi * capacity",
  "condition": "@default"
}

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Min/Max Selection

{
  "result": "min(value1, value2, value3)",
  "condition": "@default"
}

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Rounding

{
  "result": "round(value, 2)",
  "condition": "@default"
}

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Examples from Current Calculators

ReferenceIdCalculator
s_t-EU Steel Column