Negation versus Exponential
- To: mathgroup at smc.vnet.net
- Subject: [mg27123] Negation versus Exponential
- From: davidktw at mbox3.singnet.com.sg (David Kwok Tai Wei)
- Date: Sun, 4 Feb 2001 02:58:58 -0500 (EST)
- Organization: The Math Forum
- Sender: owner-wri-mathgroup at wolfram.com
I have a very simple question here should Negation (~) have a lower precedence than Exponential becoz if that's the case, ~1^2 should be evaluated as -1 instead of 1. -1 is incorrect becoz when I calculate ~1^2, I don't use brackets at all. so why must I explicitly bracket the expression --> (~1)^2, just to overcome the fault, that negation should be of higher precedence than exponential. when dealing with infix expression, computers will usually convert to postfix expression b4 evaluating them. hence a^~f will yield the postfix of a^f~, provided negation is of lower precedence than exponential. looking at the postfix, if I try to evaluate it using a stack, it will generate error becoz when I try to evaluate ^ and pop 2 operands from the stac, only one is available. On the other hand, if I set negation of higher precedence than exponential, all such errors will be solved. So why stick to the old convention where it's wrong. It's such a shame. Please reply me by emailing to davidktw at mbox3.singnet.com.sg thanks