Here is a link to the live post, not the archived one. There was a huge backlash in the community because of this post, ultimately resulting in the resignation of several mods. You can clearly see that NimbleRichMan whose account has since been deleted is not funding anything. They are on their own.
The timing of this announcement causes me to think there is something else going on. Not that I disagree with the announcement. I think the 100:1 price to earnings ratio of Facebook's IPO is overly speculative and the ability to produce valuable targeted advertising from Facebook's massive database is yet to be seen. However I strongly doubt GM had no consideration for the timing and the impact it might have to the IPO. Surely FB would know about the announcement before it was released. And they could have offered money to delay the announcement. I just can't figure out what business objective GM would have for announcing it now.
Thanks for posting this. When decrypting the P code the receiver is operating in AS mode (anti spoofing). The module that is used to decrypt it is called SAASM for Selective Availability Anti-Spoofing Module. All military receivers have them. So I had the same thought.
It's also possible it did not have current decryption keys.
The next generation of GPS, block III, will provide several new codes in different bands, and is designed for safety of life concerns such as airplane navigation. With up to 5 signals in five different bands, and some with large bandwidths and higher power, it will be significantly more difficult to jam. In such cases only a ground-based military jammer will work.
Current military GPS users have an embedded module called SAASM. It decodes the P-code to prevent spoofing, which is the process of transmitting the code at a different delay to make the device believe it is in a different location. However the current GPS codes are susceptible to jamming where GPS just fails. The M-code, which is partially deployed and scheduled to be enabled in maybe 2014, will really help prevent jamming because of it's large spreading bandwidth.
If a single transceiver transmitted one code and received another, but on the same frequency channel, the transmitted signal would overpower the received signal. I explain why in this post:
The signals will only perfectly cancel when they are separated by a distance that is exactly one half the wavelength. Assuming you separate the two transmit antennas by this distance at the carrier frequency, then there will be a limitation on the available bandwidth. This is because the further you get away from center frequency, and away from the ideal antenna spacing, the less destructive interference you will have (and the more your transmit signal will leak into your receive signal). So you will double your capacity for only narrowband channels.
The pdf gives actual numbers. I just wanted to point out that there is a limitation on bandwidth.
You might also think, "If I know what I'm transmitting, why can't I just subtract it from what I receive?" This has to do with the dynamic range of the receiver, which is a function of the number of bits in your analog to digital converter. You must attenuate your received signal so that you don't saturate your converter. Have you ever turned the volume up so loud that you begin to hear distortion? It's the same thing.
So you are receiving this loud unwanted transmit signal, and this soft receive signal. You must lower the volume so that you are not distorting the highest signal. This lowers the volume on the desired signal as well. You can lower it so much that your analog to digital converter is not able to differentiate between a 1 and a 0 anymore.
I think if you could have an A2D with enough bits that you didn't care if you received the transmitted signal, then you could just carefully subtract out the unwanted transmit signal. Maybe I should patent that? Meh. I'm probably wrong.
They also come up in digital signal processing. You might be able to code a video compression algorithm without the math, but you won't be able to understand the code (somewhat overrated) and you won't be able to come up with new DSP algorithms. I used the gradient to look for the peak in a two dimensional signal search algorithm I designed. I also used partial differential equations to solve for the solution to a set of non-linear equations for a GPS application. I think if you can add them to your toolbox, you will not regret it unless you go into web development or something.
To achieve EAL6 you must successfully pass penetration testing, and you must also have a formal methods verification which includes both the formal (mathematical) specification and that the code correctly implements the specification. EAL4 and below have the documentation requirements.
I hope the average error of the machine is zero. I assume the author of the article made a layman's statistical mistake by confusing the variance with the average. If this is the variance, then the machine will correctly determine the position of the ball to within +/- 1.9 mm only 68% of the time, and 1 out of every 100 times the machine will be off by +/- 5 mm!
Traditionally you only need n points of reference to triangulate a point in an n-dimension space. The space in question here is 4-dimensional, where the fourth unknown is time. Three satellites are adequate if you know GPS time accurate enough.
Also if you have an accelerometer and a known starting position, you can get away with one satellite in view. You take the known starting position, integrate the acceleration over time to determine the current position. The range to the other GPS satellite provides a means to correct the accelerometer errors.
No, the question is which government agency will the funding come from. The GPS program was traditionally funded by the Department of Defense. The FAA wants to use the satellites for 'life safety' applications which puts much tighter restrictions on the system, thereby increasing cost. But the FAA doesn't want to pay the hefty bill, especially for a system that is predominately DOD oriented. By the way, the contract for GPS III should be awarded I think in September 2007.
But of course, you are right. All of this money does come from taxes.
The current GPS satellites are not certified for 'life critical' applications. The next generation of GPS satellites will be certified by the FAA. So the cost comes from having to put up new GPS satellites, which you can imagine is expensive.
The nature of the holy trinity and the belief that Jesus is both fully human and fully divine were hammered out by a bunch of leaders of various christian sects, and some members of the roman government, at the council of Nicea. It was a decision of men, not of gods, which is why unlike events in the bible no one was turning sticks into snakes or being plagued or what have you.
I like your usage of the phrase "hammered out". It implies that it was not a decision that was fabricated, but was based on accepted beliefs and biblical passages. Only the details needed to be filled in. But you then say
Again, this was a decision made by men.
By which you seem to imply that the decision was completely fabricated. Whether you believe it or not, the Bible is quite internally consistent with regards to Christ's divinity. For example, there are many passages in Acts that state "God raised Jesus from the dead", e.g. 2:32, 3:26.
Then in John 2:19 it says, "Jesus answered and said to them, 'Destroy this temple, and in three days I will raise it up.'" There is little doubt (within the Biblical text) that Jesus is referring to Himself.
The council of nicea did not 'create' the notion of the trinity. It was already accepted doctrine and has a strong Biblical basis. Instead those at the council "hammered out" the details, and gave it (the concept) a name: the trinity. The result of which was the Nicean creed.
I'm sure all these things are true. However the job of the police was to drag him out of the area and arrest him if necessary. If he resisted then taze him once. If he is still capable of resisting then taze him again. I can not believe that he was capable of resisting after being tazed twice. These officers wanted to display their power.
CO2 taking as long as 20,000 years to be restored to it's natural level, but will decrease.
Why does the definition of natural always seem to exclude humans? Isn't the CO2 level always at its natural level? The assumption seems to be that humans are not part of the natural order.
1. Real DBC inherits the contracts from ancestor versions. Preconditions are or-ed together and postconditions are anded together. Invariants are also anded together. If you just use assertions you won't get this.
2. Eiffel allows you to disable the run-time execution of contracts at a fine level of detail. Again, if you use assertions you can only enable all or disable all.
3. There is no 'old' keyword in C++. Therefore you can't use 'old' in assertions.
4. According to DBC, a routine is in a transitional state during the execution of a routine. What happens if a routine calls another routine in the same class? Should it check the invariant? The answer is no. There are other cases as well.
5. It's difficult to implement a loop variant with an assertion. Not a big deal since most Eiffel code I've seen doesn't use loop variants.
If you don't want to use assertions, you can try some of the class pre-processors that are out there. You will see mixed results. In particular, I don't know of one that can handle 4. This is a show stopper.
I think you only have two choices. Use Eiffel or don't use contracts.
> -----Original Message----- > From: James Heliotis [mailto:jeh@...] > > I have a student who is interested in doing a project adding > design-by-contract assertions to another language. To my memory, > I have never seen anything about how assertions are implemented in > EiffelStudio, and what the challenges and pitfalls were. Can anyone > point me to any documentation? > > Thanks a lot, > James
Dear Jim:
Your student should find the following links useful:
Slashdot Mirror
Wait, isn't D-Wave already providing a 1000+ Qubit computer? What's the difference?
I just have a really hard time believing the Russian hacker narrative. Can't explain why. Maybe it seems too convenient for the DNC.
Here is a link to the live post, not the archived one. There was a huge backlash in the community because of this post, ultimately resulting in the resignation of several mods. You can clearly see that NimbleRichMan whose account has since been deleted is not funding anything. They are on their own.
The timing of this announcement causes me to think there is something else going on. Not that I disagree with the announcement. I think the 100:1 price to earnings ratio of Facebook's IPO is overly speculative and the ability to produce valuable targeted advertising from Facebook's massive database is yet to be seen. However I strongly doubt GM had no consideration for the timing and the impact it might have to the IPO. Surely FB would know about the announcement before it was released. And they could have offered money to delay the announcement. I just can't figure out what business objective GM would have for announcing it now.
Thanks for posting this. When decrypting the P code the receiver is operating in AS mode (anti spoofing). The module that is used to decrypt it is called SAASM for Selective Availability Anti-Spoofing Module. All military receivers have them. So I had the same thought.
It's also possible it did not have current decryption keys.
The next generation of GPS, block III, will provide several new codes in different bands, and is designed for safety of life concerns such as airplane navigation. With up to 5 signals in five different bands, and some with large bandwidths and higher power, it will be significantly more difficult to jam. In such cases only a ground-based military jammer will work.
Current military GPS users have an embedded module called SAASM. It decodes the P-code to prevent spoofing, which is the process of transmitting the code at a different delay to make the device believe it is in a different location. However the current GPS codes are susceptible to jamming where GPS just fails. The M-code, which is partially deployed and scheduled to be enabled in maybe 2014, will really help prevent jamming because of it's large spreading bandwidth.
If a single transceiver transmitted one code and received another, but on the same frequency channel, the transmitted signal would overpower the received signal. I explain why in this post:
http://tech.slashdot.org/comments.pl?sid=1997010&cid=35213010
In a CDMA system multiple transmitters send different coded signals on the same frequency where a single receiver receives the sum.
The signals will only perfectly cancel when they are separated by a distance that is exactly one half the wavelength. Assuming you separate the two transmit antennas by this distance at the carrier frequency, then there will be a limitation on the available bandwidth. This is because the further you get away from center frequency, and away from the ideal antenna spacing, the less destructive interference you will have (and the more your transmit signal will leak into your receive signal). So you will double your capacity for only narrowband channels.
The pdf gives actual numbers. I just wanted to point out that there is a limitation on bandwidth.
You might also think, "If I know what I'm transmitting, why can't I just subtract it from what I receive?" This has to do with the dynamic range of the receiver, which is a function of the number of bits in your analog to digital converter. You must attenuate your received signal so that you don't saturate your converter. Have you ever turned the volume up so loud that you begin to hear distortion? It's the same thing.
So you are receiving this loud unwanted transmit signal, and this soft receive signal. You must lower the volume so that you are not distorting the highest signal. This lowers the volume on the desired signal as well. You can lower it so much that your analog to digital converter is not able to differentiate between a 1 and a 0 anymore.
I think if you could have an A2D with enough bits that you didn't care if you received the transmitted signal, then you could just carefully subtract out the unwanted transmit signal. Maybe I should patent that? Meh. I'm probably wrong.
They also come up in digital signal processing. You might be able to code a video compression algorithm without the math, but you won't be able to understand the code (somewhat overrated) and you won't be able to come up with new DSP algorithms. I used the gradient to look for the peak in a two dimensional signal search algorithm I designed. I also used partial differential equations to solve for the solution to a set of non-linear equations for a GPS application. I think if you can add them to your toolbox, you will not regret it unless you go into web development or something.
To achieve EAL6 you must successfully pass penetration testing, and you must also have a formal methods verification which includes both the formal (mathematical) specification and that the code correctly implements the specification. EAL4 and below have the documentation requirements.
I hope the average error of the machine is zero. I assume the author of the article made a layman's statistical mistake by confusing the variance with the average. If this is the variance, then the machine will correctly determine the position of the ball to within +/- 1.9 mm only 68% of the time, and 1 out of every 100 times the machine will be off by +/- 5 mm!
That doesn't seem very trustworthy.
Is there an equivalent memristor for the mechanical world, e.g. mass, spring, dashpot, xxx?
Traditionally you only need n points of reference to triangulate a point in an n-dimension space. The space in question here is 4-dimensional, where the fourth unknown is time. Three satellites are adequate if you know GPS time accurate enough.
Also if you have an accelerometer and a known starting position, you can get away with one satellite in view. You take the known starting position, integrate the acceleration over time to determine the current position. The range to the other GPS satellite provides a means to correct the accelerometer errors.
Yes I am a GPS navigation engineer.
No, the question is which government agency will the funding come from. The GPS program was traditionally funded by the Department of Defense. The FAA wants to use the satellites for 'life safety' applications which puts much tighter restrictions on the system, thereby increasing cost. But the FAA doesn't want to pay the hefty bill, especially for a system that is predominately DOD oriented. By the way, the contract for GPS III should be awarded I think in September 2007.
But of course, you are right. All of this money does come from taxes.
The current GPS satellites are not certified for 'life critical' applications. The next generation of GPS satellites will be certified by the FAA. So the cost comes from having to put up new GPS satellites, which you can imagine is expensive.
Thanks for posting that!
You've got either a lot of Wikipedia editing, or a lot of Wikipedia reading to do. Either way, you'd better get started.
Brian
I like your usage of the phrase "hammered out". It implies that it was not a decision that was fabricated, but was based on accepted beliefs and biblical passages. Only the details needed to be filled in. But you then say
By which you seem to imply that the decision was completely fabricated. Whether you believe it or not, the Bible is quite internally consistent with regards to Christ's divinity. For example, there are many passages in Acts that state "God raised Jesus from the dead", e.g. 2:32, 3:26.
Then in John 2:19 it says, "Jesus answered and said to them, 'Destroy this temple, and in three days I will raise it up.'" There is little doubt (within the Biblical text) that Jesus is referring to Himself.
The council of nicea did not 'create' the notion of the trinity. It was already accepted doctrine and has a strong Biblical basis. Instead those at the council "hammered out" the details, and gave it (the concept) a name: the trinity. The result of which was the Nicean creed.
Brian
Maybe we should start with the Wikipedia article? From the Wikipedia article:
I'm sure all these things are true. However the job of the police was to drag him out of the area and arrest him if necessary. If he resisted then taze him once. If he is still capable of resisting then taze him again. I can not believe that he was capable of resisting after being tazed twice. These officers wanted to display their power.
You are absolutely correct.
Why does the definition of natural always seem to exclude humans? Isn't the CO2 level always at its natural level? The assumption seems to be that humans are not part of the natural order.
Here are some pitfalls you might run into:
1. Real DBC inherits the contracts from ancestor versions. Preconditions are or-ed together and postconditions are anded together. Invariants are also anded together. If you just use assertions you won't get this.
2. Eiffel allows you to disable the run-time execution of contracts at a fine level of detail. Again, if you use assertions you can only enable all or disable all.
3. There is no 'old' keyword in C++. Therefore you can't use 'old' in assertions.
4. According to DBC, a routine is in a transitional state during the execution of a routine. What happens if a routine calls another routine in the same class? Should it check the invariant? The answer is no. There are other cases as well.
5. It's difficult to implement a loop variant with an assertion. Not a big deal since most Eiffel code I've seen doesn't use loop variants.
If you don't want to use assertions, you can try some of the class pre-processors that are out there. You will see mixed results. In particular, I don't know of one that can handle 4. This is a show stopper.
I think you only have two choices. Use Eiffel or don't use contracts.
Brian
> -----Original Message-----
a a050601a.htm
e /message/3558
> From: James Heliotis [mailto:jeh@...]
>
> I have a student who is interested in doing a project adding
> design-by-contract assertions to another language. To my memory,
> I have never seen anything about how assertions are implemented in
> EiffelStudio, and what the challenges and pitfalls were. Can anyone
> point me to any documentation?
>
> Thanks a lot,
> James
Dear Jim:
Your student should find the following links useful:
http://www.phact.org/e/dennis4.html
http://mathworld.wolfram.com/CircleSquaring.html
http://chemistry.about.com/cs/generalchemistry/a/
Hope this helps,
-- Bertrand Meyer
http://tech.groups.yahoo.com/group/eiffel_softwar