Ruby is a fantastic language and is gaining some huge support in the software and web dev industries. It would be a great start for students because it teaches many fundamental concepts in programing whilst being fairly forgiving. You don't need to worry about strong typing or memory management which are things that often trip up early stage programmers.
Let the kids focus on building the code and understanding solid programming paradigms first - then let them move to C/C++ or whatever where the language is not so forgiving.
I can't vouch for the validity of "nullity" mathematically (associativity, distributivity, invertability etc) but I think people may be looking at this in the wrong way. That is, too practically. A computer would also throw an error (generally) if I try to take the square root of negative one. Of course, if you are using a math library that understands complex numbers the it will return i. i by itself is completely meaningless. What makes i powerful is some very abstract maths that has taken many years to come up with practical uses (See Euler, Fourier etc). For example, e^(i*pi) = -1 and things like fourier and laplace transorms. Who would have thought for example that knowing the complex/imaginary roots of a polynomial that does not cross the x axis could tell us the steady state error of a navigational control system?? It makes no sense at first. A lot of maths is not immediately clear in its application.
Its not just about saying I can't think of an immediate practical use for this number so I will bag it. It may take a hundred years before anyone comes up with a practical use for this. The missing link is a mathematical relationship netween nullify and the maths we already know - if there is one!
The whole point of relativity is that time is "relative". If I am travelling at 0.8c then I still age at exactly the same rate as I would on earth. Its just that 50 years to me might be 150 years to everybody back on Earth. We all still age exactly the same way in our own frame of reference. Its only when someone looks at me through a telescope that they realise I still look young whilst they have aged.
Its both power and energy. When the impedences match both the voltage across each impedence and the current though it is maximised thus maximising power. Power is simply the rate of change of energy in time. eg; a watt is a joule per second:)
Take a look at a CAT5 cable. There is practically no insulation at all so the dielectric permitivity would be hardly any better than air. Thats WHY they started twisting it so that heavy insulation wasn't needed as it is in coax.
I'm no expert but fundamentally it comes down to Maxwell's equations. A current is induced by a magnetic field in a wire by a changing magnetic field - ie; an ac signal of some frequency. Similarly, a changing electrical current in a wire will create a changing magnetic field and hence "crosstalk".
There is one caveat though and that is only the orthogonal components (to the wire) of the magnetic field induce a current and so by twisting the wires you minimize the orthogonal components.
At least that what I remember from fields studies back at uni - has been a while!
Taylor series expansions
Schrodinger's Equation
Heisenberg Uncertainty Principle
Normal Distribution Curve
Einstein's Time Dilation and relativistic equations
Newtons three laws and law of universal gravitation
Fourier's transformation(s)
The HP MSA 1500 is a SATA version of its expensive SCSI cousins. Its a fully blown storage array and you can stick up to 12 or 14 drives in an enclosure. You can attach it via SCSI or Fibre. And of course you can RAID5 it, you can have hot spares, mirrored sets, whatever you need.
I wonder, especially with the increasing number of phones with the Java Micro Edition installed, if we will soon have anti-spam software available for your mobile phone? Much the same way as there is anti email spam software for Outlook and the like.
I live in Australia and recently my girlfriend got a series of very unsolicited SMS's from an unknown number. The problem continued for several weeks until she decided to go to the police (due to their sexual nature). There was virtually nothing the police could do. Thankfully, the SMS's have now stopped but my girlfriend had no legal support at all.
There is certainly a need already for tighter controls on SMS usage - particularly unsolicited SMS (eg; SPAM). Fines are probably a good idea but tracking down and pinpointing sources of bad SMS could be a costly exercise.
I see SMS spam as a major problem that will likely get worse in the coming years!
On another note; you cannot actually determine if the rate is exponential, quadratic, quartic etc with only two points. At least three points are required.
As any two points in a plane are collinear they can always be fit to a linear rule as you stated (four times) but of course it could be a weighted exponential eg; y = k*exp(a*x). With only two points we'll never really know!
I have noticed a huge surgence of "capless" broadband plans in recent months.
Many ISP's including Dodo, escape net, TPG to name just a few have introduced unlimited download plans on their "slow" 256K/64K plans. This is fantastic news for home users except for those that have been locked into an 18 month contract with Telstra and are still capped at 3GB.
Incidently, though Australia's broadband usage is only 2% Nationally - it is actually increasing exponentially. Total number of ADSL/Cable users increased from 15,000 in July 2001 to almost 60,000 in June 2002 and it is still increasing rapidly. (See the ACCC)
Though growth may have slowed recently a little due to general unhappiness with Telstra's monopoly and bandwidth caps I see the influx of new ISP's and uncapped plans (thanks to comindico) as a good sign of more growth to come.
I agree,
By putting this capability into netfilter you could also vastly improve on IP Accounting. Now not just accounting by service port but also by Application!
If every email is taxed, services like hotmail and yahoo would be innaccessible to people like teenagers. As they would most likely need a credit card to pay for the account.
Of course, if there is a tax free threshold of say 5000 emails per annum, whats stopping potential spammers from signing up to one account, sending 5000 emails, signing up to another account, sending another 5000 emails and so on...?
65% of security breaches occur from INSIDE the network
I can't speak for World Wide statistics but according to the Australian Bureau of Deloitte Touch Tohmatsu in a survey they conducted in 2002 - 65% of breaches in security occured from within the network.
The survey also compares itself to a similar survey conducted by the American FBI which gave similar results in the same year.
Interestingly, (horrifyingly!) 98% of respondents claimed to be the victim of some sort of computer crime!
A LED is just a diode after all and like all diodes it has a capacitance.
This is the only thing that will truly limit performance at high frequencies. Eventually, as frequency is increased you will get a low pass filter effect and the led will begin to dim.
As far as I am aware most LED's have a capacitance of only a few pF so depending on the current rating and duty cycle there should be a half power point well above 10kHz.
Incidentally, the duty cycle will affect the frequency range. A 50/50 duty cycle or square wave input will have a sinusoidal fundamental at the pulse frequency and a series of harmonics which may be above the half power cutoff of the led. Hence you are effectively putting a sinusoid accross the LED.
Other duty cycles will have different harmonic content and hence will behave differently near the frequency cutoff. (Do a fourier analysis!)
There will be a point some distance away from the earth, for a given payload mass where the gravitational force balances the outward inertial force (also taking into account that the payload may be accelerated mechanically as well).
Below this point the payload will fall back to earth and above it the payload will fly off into space.
Neither is pretty! I don't which I'd rather - falling from a few thousand metres and being splattered or spending my last days running out of air hurtling AWAY from earth!
Slashdot Mirror
Ruby is a fantastic language and is gaining some huge support in the software and web dev industries. It would be a great start for students because it teaches many fundamental concepts in programing whilst being fairly forgiving. You don't need to worry about strong typing or memory management which are things that often trip up early stage programmers. Let the kids focus on building the code and understanding solid programming paradigms first - then let them move to C/C++ or whatever where the language is not so forgiving.
I use LLPR => Linux, Lighttpd, Postgresql, Rails :)
I can't vouch for the validity of "nullity" mathematically (associativity, distributivity, invertability etc) but I think people may be looking at this in the wrong way. That is, too practically. A computer would also throw an error (generally) if I try to take the square root of negative one. Of course, if you are using a math library that understands complex numbers the it will return i. i by itself is completely meaningless. What makes i powerful is some very abstract maths that has taken many years to come up with practical uses (See Euler, Fourier etc). For example, e^(i*pi) = -1 and things like fourier and laplace transorms. Who would have thought for example that knowing the complex/imaginary roots of a polynomial that does not cross the x axis could tell us the steady state error of a navigational control system?? It makes no sense at first. A lot of maths is not immediately clear in its application.
Its not just about saying I can't think of an immediate practical use for this number so I will bag it. It may take a hundred years before anyone comes up with a practical use for this. The missing link is a mathematical relationship netween nullify and the maths we already know - if there is one!
The whole point of relativity is that time is "relative". If I am travelling at 0.8c then I still age at exactly the same rate as I would on earth. Its just that 50 years to me might be 150 years to everybody back on Earth. We all still age exactly the same way in our own frame of reference. Its only when someone looks at me through a telescope that they realise I still look young whilst they have aged.
I will be very interested to see what NASA has in store for after the shuttle program. Or will the private sector take up the slack? :)
FP
Anyone remember Transmeta? Well check out what they do now!
http://orionmulti.com/
Its both power and energy. When the impedences match both the voltage across each impedence and the current though it is maximised thus maximising power. Power is simply the rate of change of energy in time. eg; a watt is a joule per second :)
Take a look at a CAT5 cable. There is practically no insulation at all so the dielectric permitivity would be hardly any better than air. Thats WHY they started twisting it so that heavy insulation wasn't needed as it is in coax.
I'm no expert but fundamentally it comes down to Maxwell's equations. A current is induced by a magnetic field in a wire by a changing magnetic field - ie; an ac signal of some frequency. Similarly, a changing electrical current in a wire will create a changing magnetic field and hence "crosstalk".
There is one caveat though and that is only the orthogonal components (to the wire) of the magnetic field induce a current and so by twisting the wires you minimize the orthogonal components.
At least that what I remember from fields studies back at uni - has been a while!
Oh, ok. Jerk is the rate of change of acceleration....and I just thought you were calling him a jerk!
Acceleration is the second derivative of a position function related to time! Not the third!
x = f(t)
v = dx/dt = f'(t)
a = dv/dt = f''(t)
MSI make something similar and have a few different models. MSI's look better I think but functionally they're very similar.
Here's the link
Taylor series expansions
Schrodinger's Equation
Heisenberg Uncertainty Principle
Normal Distribution Curve
Einstein's Time Dilation and relativistic equations
Newtons three laws and law of universal gravitation
Fourier's transformation(s)
The HP MSA 1500 is a SATA version of its expensive SCSI cousins. Its a fully blown storage array and you can stick up to 12 or 14 drives in an enclosure. You can attach it via SCSI or Fibre. And of course you can RAID5 it, you can have hot spares, mirrored sets, whatever you need.
I think annoyance is the MAJOR problem. Why else would email SPAM be a problem?
I wonder, especially with the increasing number of phones with the Java Micro Edition installed, if we will soon have anti-spam software available for your mobile phone? Much the same way as there is anti email spam software for Outlook and the like.
I live in Australia and recently my girlfriend got a series of very unsolicited SMS's from an unknown number. The problem continued for several weeks until she decided to go to the police (due to their sexual nature). There was virtually nothing the police could do. Thankfully, the SMS's have now stopped but my girlfriend had no legal support at all.
There is certainly a need already for tighter controls on SMS usage - particularly unsolicited SMS (eg; SPAM). Fines are probably a good idea but tracking down and pinpointing sources of bad SMS could be a costly exercise.
I see SMS spam as a major problem that will likely get worse in the coming years!
On another note; you cannot actually determine if the rate is exponential, quadratic, quartic etc with only two points. At least three points are required.
As any two points in a plane are collinear they can always be fit to a linear rule as you stated (four times) but of course it could be a weighted exponential eg; y = k*exp(a*x). With only two points we'll never really know!
This is seriously off topic!
Of course! I use the term exponential in its vanacular sense - ie; loosely!
I have noticed a huge surgence of "capless" broadband plans in recent months.
Many ISP's including Dodo, escape net, TPG to name just a few have introduced unlimited download plans on their "slow" 256K/64K plans. This is fantastic news for home users except for those that have been locked into an 18 month contract with Telstra and are still capped at 3GB.
Incidently, though Australia's broadband usage is only 2% Nationally - it is actually increasing exponentially. Total number of ADSL/Cable users increased from 15,000 in July 2001 to almost 60,000 in June 2002 and it is still increasing rapidly. (See the ACCC)
Though growth may have slowed recently a little due to general unhappiness with Telstra's monopoly and bandwidth caps I see the influx of new ISP's and uncapped plans (thanks to comindico) as a good sign of more growth to come.
I agree,
By putting this capability into netfilter you could also vastly improve on IP Accounting. Now not just accounting by service port but also by Application!
If every email is taxed, services like hotmail and yahoo would be innaccessible to people like teenagers. As they would most likely need a credit card to pay for the account.
Of course, if there is a tax free threshold of say 5000 emails per annum, whats stopping potential spammers from signing up to one account, sending 5000 emails, signing up to another account, sending another 5000 emails and so on...?
Most security breachings occur from within.
65% of security breaches occur from INSIDE the network
I can't speak for World Wide statistics but according to the Australian Bureau of Deloitte Touch Tohmatsu in a survey they conducted in 2002 - 65% of breaches in security occured from within the network.
The survey also compares itself to a similar survey conducted by the American FBI which gave similar results in the same year.
Interestingly, (horrifyingly!) 98% of respondents claimed to be the victim of some sort of computer crime!
A LED is just a diode after all and like all diodes it has a capacitance.
This is the only thing that will truly limit performance at high frequencies. Eventually, as frequency is increased you will get a low pass filter effect and the led will begin to dim.
As far as I am aware most LED's have a capacitance of only a few pF so depending on the current rating and duty cycle there should be a half power point well above 10kHz.
Incidentally, the duty cycle will affect the frequency range. A 50/50 duty cycle or square wave input will have a sinusoidal fundamental at the pulse frequency and a series of harmonics which may be above the half power cutoff of the led. Hence you are effectively putting a sinusoid accross the LED.
Other duty cycles will have different harmonic content and hence will behave differently near the frequency cutoff. (Do a fourier analysis!)
It could fall back to earth!
There will be a point some distance away from the earth, for a given payload mass where the gravitational force balances the outward inertial force (also taking into account that the payload may be accelerated mechanically as well).
Below this point the payload will fall back to earth and above it the payload will fly off into space.
Neither is pretty! I don't which I'd rather - falling from a few thousand metres and being splattered or spending my last days running out of air hurtling AWAY from earth!