pentaho/pentaho-kettle · error · KettleValueException

Function COS only works with a number

Error message

Function COS only works with a number

What it means

The cos() method of Kettle's legacy Value class computes the cosine of the value (in radians) via Math.cos. If the Value is not numeric it throws this KettleValueException, because the underlying Java Math call requires a double. Type enforcement is done at runtime by the legacy compatibility Value class.

Solutions

1. Convert the Value to Number before calling cos() (setType(VALUE_TYPE_NUMBER))
2. Fix the input step so the field is declared numeric
3. Guard with isNumeric() and convert or skip non-numeric rows

Example fix

// before
Value result = angle.cos(); // angle is a String
// after
angle.setType(Value.VALUE_TYPE_NUMBER);
Value result = angle.cos();

if (value == null || !value.isNumeric()) {
  throw new IllegalArgumentException("COS requires a numeric value, got type " + (value == null ? "null" : value.getType()));
}

boolean isNumericValue(Value v) { return v != null && v.isNumeric(); }

try {
  result = value.cos();
} catch (KettleValueException e) {
  value.setType(Value.VALUE_TYPE_NUMBER);
  result = value.cos();
}

When it happens

Trigger: Calling Value.cos() when the Value holds a String, Date, Boolean or other non-numeric type - typically an angle value read as text and not converted.

Common situations: Trigonometric calculations in legacy JavaScript/Formula steps; angle columns from Excel/CSV inputs typed as String; transformations where a type-conversion step was deleted.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Function ACOS only works with numeric data
• Function ASIN only works with numeric data
• Function ATAN only works with numeric data
• Function ATAN2 only works with numbers
• Function CEIL only works with a number

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/4ff4e9d62fb4c899. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/compatibility/Value.java:2456

    if ( isNumeric() ) {
      setValue( Math.ceil( getNumber() ) );
    } else {
      throw new KettleValueException( "Function CEIL only works with a number" );
    }
    return this;
  }

  // implement the COS function, arguments in args[]
  public Value cos() throws KettleValueException {
    if ( isNull() ) {
      return this;
    }

    if ( isNumeric() ) {
      setValue( Math.cos( getNumber() ) );
    } else {
      throw new KettleValueException( "Function COS only works with a number" );
    }
    return this;
  }

  // implement the EXP function, arguments in args[]
  public Value exp() throws KettleValueException {
    if ( isNull() ) {
      return this;
    }

    if ( isNumeric() ) {
      setValue( Math.exp( getNumber() ) );
    } else {
      throw new KettleValueException( "Function EXP only works with a number" );
    }
    return this;
  }

View on GitHub (pinned to f3058517a1)