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Why Computers Suck At Math
antdude writes "This TechRadar article explains why computers suck at math, and how simple calculations can be a matter of life and death, like in the case of a Patriot defense system failing to take down a Scud missile attack: 'The calculation of where to look for confirmation of an incoming missile requires knowledge of the system time, which is stored as the number of 0.1-second ticks since the system was started up. Unfortunately, 0.1 seconds cannot be expressed accurately as a binary number, so when it's shoehorned into a 24-bit register — as used in the Patriot system — it's out by a tiny amount. But all these tiny amounts add up. At the time of the missile attack, the system had been running for about 100 hours, or 3,600,000 ticks to be more specific. Multiplying this count by the tiny error led to a total error of 0.3433 seconds, during which time the Scud missile would cover 687m. The radar looked in the wrong place to receive a confirmation and saw no target. Accordingly no missile was launched to intercept the incoming Scud — and 28 people paid with their lives.'"
Hindsight is almost 20/20. Except that the original purpose of the Patriot was to shoot down much slower aircraft, flying parallel to the earth, not ballistic missles. This new use for Patriot was essentially experimental and had had been rushed to war - and in war you run into alot of unexpexcted circumstances. For example, conventional doctrine in the 1980's required Patriots to move constantly on the battlefield to avoid air attack. The clock would then reset when repositioned. No one expected a Patriot in air defense mode to stay stationary for 10 hours let alone 100. But in a missle defense role they did. There is a good GAO report on this.
The Iron dome system works perfectly. It's just not capable of protecting any kind of large area. It can, however, make a military base invulnerable to rocket fire, and they're working on making the system mobile, to protect tanks. The only real problem left for doing this is the power requirements.
For ships, another such system exists, and protected the ships perfectly well from those same rockets fired by hizbullah. It's "protection range" ? In the largest deployment about 200 square meters.
There is also the problem that a downed missile presents. What is a "downed missile" ? Well it's a large collection of very-high speed pieces of metal that have been heated up by a large explosion that's about to crash into the ground. So far so good.
So what is "the ground" in the case of a hizbullah or hamas missile launch ? Well it's the center of the city that's controlled by the terrorists. It's their human shields. Markets, schools, you name it. So a successfull missile intercept is reported in the press as "Israel fires a rocket into a palestinian kindergarten". That is, by the way, the literal truth, even if the rather important detail of a rocket's presence above said kindergarten is left out. In the deployed missile intercept installations "the ground" is chosen to be something else, like the ocean surface.
Missile intercept systems are no solution for terrorism. Most unfortunately, the only solution for those rocket attacks is preventing they're fired in the first place. Which obviously requires either palestinians police their own terrorists, or someone does it for them (that's called "occupation").
These systems work, they are deployed successfully in the field. They're no silver bullets, and any bullet that's fired, whether a missile or a missile-intercept-missile, will eventually hit the ground at rather high speeds. Which makes their use above urban environments result in civilian casualties.
1. The Patriot version used in the Gulf War (round 1) was not designed to be used against Tactical Ballistic Missiles (like SCUDs), but against opposition aircraft. A fighter isn't going to be flying as fast, and thus the error is going to be much smaller, which means the missile would probably still find the plane.
2. The Patriot has a quite good record against SCUDs (after the software upgrades). Much better than the Soviet SA-2s did against B-52 raids in Vietnam.
3. Systems don't always work right the first time, and if you do a full on test to start with, and something goes wrong, it's a lot harder to find where the error is than if you test one part at a time.
Uhh hezbolah was created to defend lebanon in the 80s after israel killed thousands of lebanese and occupied a good chunk of it.
The last fight between them happened in 2006. Hezbolah kidnapped a few SOLDIERs to trade for PoWs (a common thing since israel has a shit ton of prisoners).
Israel responded by sending in an army many 100s of times larger than lebanon's they bombed many buildings including hospitals, school, UN bunkers and apartment buildings. Hezbolah fired rockets back to show resistance.
In the end Israel killed 1200 civilians, 300soldiers, and a significant percentage of the countries economy. Hezbolah killed 120soldiers, 40civilians. Notice the fucking difference in ratios. Oh and the whole time hezbolah conducted rescue missions, gave out food and helped transport people to safety. So fuck off.
Also: "Hezbollah is now also a major provider of social services, which operate schools, hospitals, and agricultural services for thousands of Lebanese Shiites, and plays a significant force in Lebanese politics.".
Also hezbolah states that they distinguish between zionists and jewish. Their stated reason for firing rockets is continued resistance against israeli attacks and to put an end to any colonial entity within lebanon. NOT kill jews.
How the fuck parent got modded up is beyond me. Every single point is a verifiable falsehood.