John Cuthber

Do you take the same view on different varieties of apples? For example are you concerned that Golden Delicious may be harmful even though Cox's Orange Pippins are not?

And some cut flowers last longer if you put a little sugar in the water in the vase.

is this the sort of thing you are after? http://www.techonthenet.com/excel/formulas/if_nested.php

Demonstrably wrong. All over the world there are compressed air containers that are full of high pressure air. Someone already took lots of air from the atmosphere and put it into those containers. Yet balloons still rise And why is there a difference between a heavy gas and a light gas? They both push the atmosphere up equally well. If that was the cause of lift they would both float equally well. Also, you have not explained how a balloon on a string can generate electricity by rising unless that energy is taken from the potential energy of the balloon. If energy is taken from it as it rises then it must have less potential energy when it's high up.

You seem to be muddling up two things. The rubber from which the balloon is made gains potential energy when it rises. However, the helium in the balloon loses potential energy as it rises. So, if the balloon bursts then the rubber falls - fair enough. But if you consider the balloon and the helium together (and that's what the phrase "helium balloon" means then it loses potential energy as it rises. And I'm not going to repeat the details but the fact that the balloon loses potential energy as it rises is the reason why you could extract energy from the system with a bit of string and a generator. If, as you claim, the balloon ends up with more energy after it has done work turning the generator, where did that energy come from? The other thing you have missed is this "It can only go into the balloon. Do you not agree?" Yes, but it goes initially into the kinetic energy of the balloon and it subsequently dissipated as heat by viscosity.

...and the thread is about batteries. As for the people writing about cathodes in pages about batteries- well, they clearly haven't read what Mr Faraday wrote.

True, but if the answer to the original question is tautologically "no" then there's no fun to be had debating it.

Fundamentally there's an implicit conditional branch of sorts in the logic In the memory there's some sort of circuitry that chooses the right flip-flop (or capacitor or whatever) to store data in. Something like the tiny scarp of circuitry shown. Well, the gates in that are conditional. the output of an AND gate is conditional on its inputs. At that level, since it's not possible to make a digital computer without gates, it's not possible to make a programme that runs without conditional branching. I might have to think a bit to see it f it can be done with an analogue computer (without comparators).

As I said "The tricky part is programming the ROM." Fortunately for me, having pre-calculated the states of play is part of the original design brief: "Are if statements unnecessary if a program is represented as an explicit state machine with precomputed states?" I grant you that calculating them would need a conventional programme (and a long one at that). But, once I have the table I can look up the outputs for any programme as long as it has finite possible inputs and finite possible outputs. If, on the other hand, we look at programmes that have infinitely wide ranges of inputs and outputs, they might never finish. So, OK I can't calculate all the digits of pi without using an If statement. But you can't write a programme that tells me all the digits of pi with if statements. I just did.

I seem to have screwed op the typing a bit there the line you have quoted is out of place. It should be just before "The tricky part is programming the ROM." So that might affect your reply but I don't see how it can be relevant. There is no loop. and All the memories, though huge, are finite (and almost all of them are fixed ROMs). (except the "accidental" one where if you keep incrementing the "time" for long enough it will roll over to all zeroes again which is fine- the last two hundred or so instructions put a message on the screen saying it concedes. A second after the 100 years is up, the game starts over from scratch) "How are you going to prepare in advance infinite quantity set for infinite large number? " What infinitely large number?

And, once more I will point out that nobody said it would be practical. Ok, so here's how to design the computer that plays space invaders without an IF statement. You need a really big stack of ROM memories (don't bother trying to do this at home, Sensei's arithmetic has already shown it won't fit into the universe). Each one needs some address data- specifically, it needs the inputs from the joystick and so on, and also it needs a wide enough address bus to map the whole of the display memory as an input (That memory is an out put too but I will get back to it) So, the address bus is something like 49766400 bits wide (Plus a few more for the joystick etc) And, you need a memory of that size for each time point So you need something like 3E11 of those memory chips. Each memory address must point to some stored data- a wide enough word to include the screen and the sound generators. And, of course it needs a wide enough data bus to spit that data out. We then take that data and put it into a temporary store (that component is one of the few that's perfectly reasonable. We also need a clock. We can have that tick at 200 Hz. It needs a bit more hardware to do the synchronisation but the simplified version is that on every odd numbered clock cycle, it transfers the output from the huge memory to the output memory (and copied it to the screen- that's a massive parallel transfer but it's also roughly the throughput of the optic nerve) On the even numbered clock cycles it increments a timer by 1 and feeds that to a 1 of 3E11 selector which selects the memory we are looking at. It copies the output memory to the input address bus and it also copies the inputs from the joystick etc to the relevant bits of the address bus. The tricky part is programming the ROM. It needs to know what to send to the screen in any given circumstances of how long the game has been in play, what buttons the player is pressing and (here's the bit that makes it deterministic) the current state of the output- i.e. what's on the screen (and the sound generator). The screen acts not just as an output, but also as the "working memory" So, for example, the score isn't remembered explicitly as a score and incremented when he hits something, it is remembered as a pattern of dots on the screen. OK, it's fair to say that Atari are not going to be adopting this any time soon but there are two important things to note. The first is that it is , in principle, possible to write a Space Invaders game without using a single IF statement. (That's what the thread was about) There's another point. How else can you write a Space Invaders game with a 200Hz clock rate? There are circumstances where that increase in effective speed outweighs the impracticality of calculating all the answers in advance. That's also why, if I ask you what five times nine is, you remember the answer, rather than counting it out on your fingers. It also enables the memory chip so it outputs the data stored in the relevant address of the rom to the output memory

OK, big numbers. So? Incidentally, you forgot the potential need to refresh them 100 times a second for a century. That's roughly 3E11 time points you need. However,nobody said this would be sensible or practical.

Odd as it may seem, I didn't say I'd provide code. Lets make a few assumptions. The person playing doesn't have infinitely fast reflexes. For the sake of having a number, let's say he doesn't react to a change on the screen, or press a button in less than 0.01 seconds He won't live forever. For the sake of discussion, can we keep the condition that if he's still playing after 100 years, the computer concedes defeat? The input to the machine is a few switches - a joystick , fire button and perhaps a couple of other controls. (It doesn't really matter how many inputs there are as long as it's finite so you can have a trackball or some such if you want. . If you do that I will say we can connect it to a couple of A to D converters and just have a dozen or so inputs for x and y) The outputs are a screen- we can easily model that as being memory mapped more or less directly to an LCD device- and a sound generator. That sound generator has a handful of inputs which turn it on or off an d decide the pitch (there might be a few "voices" if it needs to be polyphonic or to do speech synthesis or whatever) Happy so far?

A conditional branch is what an "If" statement lets you do. It transfers program control to one of two (or more) places depending on some parameter or other. I said conditional branching because it's possible to et the same effect as an "if" statement by using other functions or operations. In VBA you can use Select Case to achieve the same sort of thing. Do you think it is possible to write a 100 year space invaders game without using an If statement (or its logical equivalent)?

I did already specify a finite system... But a real player would eventually die. Also, the usual game speeds up as time goes on so it's impossible for a real human to play it. If nothing else, eventually the machine won't have enough memory to remember the score. So, what about a computer game that goes on for no more than 100 years, because at that point it concedes defeat and announces that the player won? Do you think that would that be complex enough to need conditional branching?

I have a worrying feeling that most parts of most scripture get misinterpreted somewhere, often deliberately.

I'm in two minds about discussing that: it's hardly on topic, but I don't see this topic going anywhere anyway. If the steel rods in typical pre-stressed concrete lintels + such were not anchored to the concrete, they wouldn't work. A much more interesting (and much more on-topic) question is why did the patent authorities think it was "novel" enough to award a patent?

The force can be calculated as m v^2/r no matter whether it's real or not.

Ok fair enough. (Though it depends on POV, the stress is post assembly, but pre earthquake) In any case, it still seems to me to be little more than a high tech guy rope.

You don't need to. It's wrong anyway (unless the "proper" interpretation is so obscure as to make the terms meaningless.) From the point of view of someone who believes the whole "God" thing, it's still wrong, because you can't steal heaven.

You seem to have reinvented pre-stressed concrete. http://en.wikipedia.org/wiki/Prestressed_concrete Also the commentary in the video says "the building does not achieve an S shape due to the inertia of the floor plates." If the bottom floor is displaced to the left then the right then the left again by the quake then a wave will propagate up the building. If those changes are fast enough then it will not have reached the top before it changes direction at the bottom. It will become S shaped.

Well, if you say the only problem that philosophers can solve is giving clarity, and you can't provide clarity to those threads then either you are not a philosopher or you were mistaken.

I realise there's no more than the slightest evidence that the Bible is anything other "than made up stuff". But that's not the point. Either the Bible is right; there is a "kingdom of heaven", and that story is wrong because it's not something you could pinch like a bag of gold, or The bible is wrong, there is no such thing as a "kingdom of heaven" and the story is wrong because it's not something you could pinch like a bag of gold. The assertion is wrong, pretty much regardless of one's theological position.

Hard to say, but could there be manganese in the Fe2O3? It's fairly easy to get manganates under those conditions (very alkaline, strongly oxidising and hot): manganates are green.