void throwOnIncompatibleType(TensorType type) {
        if ( ! this.type().isRenamableTo(type))
            throw new IllegalArgumentException("Can not change type from " + this.type() + " to " + type +
                                               ": Types are not compatible");
    }
Returns the value at the given <i>standard value order</i> index as a float.

@param valueIndex the direct index into the underlying data.
@throws IllegalArgumentException if index is out of bounds
vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java