public static PrefixOperation getPrefixOperation(String type, Expression param){
		String noSpace = type.replaceAll("\\s+","");
		String s = noSpace.toLowerCase();
		if( "sin".equals(s) ){
			return new Sin( param );
		} else if ("cos".equals(s) ){
			return new Cos( param );
		}  else if ("tan".equals(s) ){
			return new Tan( param );
		}  else if ("ln".equals(s) ){
			return new Ln( param );
		} else {
			throw new Error("Unrecognized Prefix Operation."
					+ "This error might actually happen");
		}
		
	}