pentaho/pentaho-kettle · error · KettleValueException

Function TAN only works on a number

Error message

Function TAN only works on a number

What it means

Thrown by Value.tan() when the value is not numeric. TAN computes Math.tan(getNumber()) behind an isNumeric() guard; String, Date, Boolean, and Binary values raise KettleValueException. Nulls return early with no error.

Solutions

1. Guard with value.isNumeric() before calling tan().
2. Convert the angle field to Number before applying TAN.
3. Correct the field type in the input step or a 'Select values' step.
4. Catch KettleValueException and route bad rows to error handling.

Example fix

// before
Value t = value.tan(); // throws for String-typed value
// after
Value t = value.isNumeric() ? value.tan() : new Value(value.getName(), Math.tan(Double.parseDouble(value.getString())));

if (!value.isNumeric()) { throw new IllegalArgumentException("TAN requires a numeric angle"); }

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

try { result = value.tan(); } catch (KettleValueException e) { result = null; }

When it happens

Trigger: Calling value.tan() on a non-numeric Value, most often an angle stored as String.

Common situations: Trigonometric transformations on text-file columns; angle data ingested as strings; using TAN on mis-typed field metadata.

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 SIN only works with a number
• BaseStep.SafeMode.Exception.MixingTypes
• DynamicSQLRow.Exception.TemplateReturnDataTypeError
• ElasticSearchBulk.Error.NoJsonFieldFormat
• Function MOD only works with numeric data

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/131afaacdcd02af3. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/compatibility/Value.java:3022

  }

  // implement the SYSDATE function, arguments in args[]
  public Value sysdate() {
    setValue( Calendar.getInstance().getTime() );

    return this;
  }

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

    if ( isNumeric() ) {
      setValue( Math.tan( getNumber() ) );
    } else {
      throw new KettleValueException( "Function TAN only works on a number" );
    }

    return this;
  }

  // implement the TO_CHAR function, arguments in args[]
  // number: NUM2STR( 123.456 ) : default format
  // number: NUM2STR( 123.456, '###,##0.000') : format
  // number: NUM2STR( 123.456, '###,##0.000', '.') : grouping
  // number: NUM2STR( 123.456, '###,##0.000', '.', ',') : decimal
  // number: NUM2STR( 123.456, '###,##0.000', '.', ',', '?') : currency

  public Value num2str() throws KettleValueException {
    return num2str( null, null, null, null );
  }

  public Value num2str( String format ) throws KettleValueException {
    return num2str( format, null, null, null );

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