pentaho/pentaho-kettle · error · KettleValueException

Function ACOS only works with numeric data

Error message

Function ACOS only works with numeric data

What it means

In Pentaho Kettle's legacy org.pentaho.di.compatibility.Value class, the acos() method computes the arc cosine of the value. Before doing so it checks isNumeric(); if the Value holds a non-numeric type (string, date, boolean, etc.) it throws this KettleValueException because Math.acos requires a double. The legacy Value class performs these explicit runtime type checks instead of relying on the compiler.

Solutions

1. Convert the Value to a number before calling acos(), e.g. value.setType(Value.VALUE_TYPE_NUMBER) or use the appropriate conversion method
2. Fix upstream field metadata so the column arrives as Number (Numeric type in Select values / Text file input)
3. Guard the call with if (value.isNumeric()) and handle the non-numeric branch explicitly

Example fix

// before
Value result = value.acos();
// after
if (!value.isNumeric()) {
  value.setType(Value.VALUE_TYPE_NUMBER); // convert string/other to number
}
Value result = value.acos();

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

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

try {
  result = value.acos();
} catch (KettleValueException e) {
  // value was non-numeric: convert and retry or fail the row
  value.setType(Value.VALUE_TYPE_NUMBER);
  result = value.acos();
}

When it happens

Trigger: Calling Value.acos() on a Value whose type is not VALUE_TYPE_NUMBER/INTEGER/BIGNUMBER - e.g. a field read from a text file column that stayed a String, or a null-typed Value that was not converted first.

Common situations: JavaScript/formula-like transform steps that call mathematical functions on fields typed as String; CSV/Excel inputs where a numeric column was inferred as String due to formatting characters; migrating old Kettle transformations where Value type conversion steps were removed.

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 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
• Function COS only works with a number

AI-assisted analysis of pentaho/pentaho-kettle@f3058517a1 (2026-09-13). Data as JSON: /api/errors/350f98d6deb927a1. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/org/pentaho/di/compatibility/Value.java:2382

      setValue( Math.abs( getNumber() ) );
    } else if ( isInteger() ) {
      setValue( Math.abs( getInteger() ) );
    } else {
      throw new KettleValueException( "Function ABS only works with a number" );
    }
    return this;
  }

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

    if ( isNumeric() ) {
      setValue( Math.acos( getNumber() ) );
    } else {
      throw new KettleValueException( "Function ACOS only works with numeric data" );
    }
    return this;
  }

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

    if ( isNumeric() ) {
      setValue( Math.asin( getNumber() ) );
    } else {
      throw new KettleValueException( "Function ASIN only works with numeric data" );
    }
    return this;
  }

View on GitHub (pinned to f3058517a1)