In programming languages, a type system is a logical system comprising a set of rules that assigns a property called a type to the various constructs of a computer program, such as variables, expressions, functions or modules. These types formalize and enforce the otherwise implicit categories the programmer uses for algebraic data types, data structures, or other components (e.g. "string", "array of float", "function returning boolean"). The main purpose of a type system is to reduce possibilities for bugs in computer programs by defining interfaces between different parts of a computer program, and then checking that the parts have been connected in a consistent way. This checking can happen statically (at compile time), dynamically (at run time), or as a combination of both. Type systems have other purposes as well, such as expressing business rules, enabling certain compiler optimizations, allowing for multiple dispatch, providing a form of documentation, etc.
A type system associates a type with each computed value and, by examining the flow of these values, attempts to ensure or prove that no type errors can occur. The given type system in question determines what constitutes a type error, but in general, the aim is to prevent operations expecting a certain kind of value from being used with values for which that operation does not make sense (logic errors). Type systems are often specified as part of programming languages and built into interpreters and compilers, although the type system of a language can be extended by optional tools that perform added checks using the language's original type syntax and grammar.
Homework Statement
Is Xe a molecular, metallic, ionic, or network covalent solid?
2. The attempt at a solution
Xe is not molecular (single atom)
Xe is not metallic or ionic.
Xe is not not network covalent (xenon atoms have a stable electron configuration and don't form covalent bonds with each...
Hi All,
I would like to make a glove with a small transmitter antenna on the index finger. A small receiver similar to a LoJack device would track the finger. The device would need to be extremely accurate to follow small movement (1 mm?) of the transmitter. I’ve made a device that uses an IR...
Hello all,
I am after some advice regarding a hall sensor type air flow meter.
I know from experience that most hall sensor flow meters allow a bypass of fluid around the turbine/fan. However I would like to know what would happen if this was the case of the design below.
Specifications...
Homework Statement
Homework EquationsThe Attempt at a Solution
How is the regions in the given decomposition both type 1 and type 2 regions at the same time? Take the region at the upper right hand side as an example. It can't be neither type 1 and type 2 regions because the functions that...
I've finally worked out a derivation of the Lorentz transformation that doesn't use the now out of favor i^2=-1, but it still has one weak spot: it assumes that the transformation is linear. It seems quite reasonable to me that it would be linear since it has to graph straight lines on to...
If you count the frequency of letters in a message, then have one axis with letters and another with numbers, is that a histogram or a bar graph or something different still?
I'm curious if anyone/any member of the forum has used newer methods like twitter, to try to regain employment in some earlier type of work that one had from a long time ago. Instead of the typical job search of going to advertisements, calling companies, finding managers to talk to by phone...
I decided to go deep in physics theories such as QFT, general QM and Special/General Relativity. Would it be better to spend a lot of time, say, 1+ year, learning through the most complete math books or just use books that mix math and physics to learn the necessary and suficient math and go to...
Why all particles of same type identical? All electrons are identical to each other, all protons are identical..etc. It is as if they are copy pasted from each other!
For me this is one of the biggest mysteries ever, why we don't detect more massive or less massive electrons?
Is it related...
Hello everyone,
for health reason, I just need to know from you what kind of antenna is the one in the photo attached, if it is a receiver or a transmitter and if it is safe enough.
I will have to move on the first floor of a house right under that building (which is a police station if it can...
Homework Statement
Suppose this the velocity time graph given and we want to plot position time grah from this.
What are the things to be considered while plotting the position time graph from this graph?
2. Homework Equations
The uniform acceleration motion equations.
The Attempt at a...
Take note of today's Obied-Ooguri-Spodyneiko-Vafa 18.
Curious situation: After it had influenced much the development of the string theory community’s attention and almost all of its public media perception since 2003, after what must be thousands of followup publications, the argument of KKLT...
I am aware that hypergeometric type differential equations of the type:
can be solved e.g. by means of Mellin transforms when σ(s) is at most a 2nd-degree polynomial and τ(s) is at most 1st-degree, and λ is a constant. I'm trying to reproduce the method for the case where λ is not constant...
Convolution has the form
(f\star g)(t) = \int_{-\infty}^{\infty}f(\tau)g(t-\tau)d\tau
However, I for my own purposes I have invented a similar but different type of "convolution" which has the form
(f\star g)(t) = \int_0^{\infty}f(\tau)g(t/\tau)d\tau
So instead of shifting the function g(t)...
Targeting epigenetic maintenance of beta cell identity should be actively explored -
https://medicalxpress.com/news/2018-06-diabetes-results-breakdown-epigenetic.html
Tess Tsai-Hsiu Lu et al. The Polycomb-Dependent Epigenome Controls β Cell Dysfunction, Dedifferentiation, and Diabetes, Cell...
Hallo All!
Im glad to be here...
I have written a paper on a new type of network for NLP but i have lingering questions on how efficient and effective it is...this is a link to it on my blog...
ABSTRACT submited
So the following is a more formal framing of efficiency and effectiveness in...
I was reading this paper
https://arxiv.org/pdf/0805.4725.pdf
It seems that the potential between the particles can be assumed of different forms, shouldn't the potential be a solution of the problem.
Thanks
I'm wondering if for example YBCO superconductor (which is considered type-II superconductor) that exhibits flux pinning effect is a bulk or some substrate with YBCO film on top of it?
I always thought that YBCO which exhibits flux pinning is a bulk in all of demonstration videos but it struck...
This is the AN/APG-81 AESA Radar antenna by Northrop Grumman currently found in the F-35 (photo from wikipedia article).
It seems to have a very different structure than past AESA/PESA antennas. For example the APG-68 from the F-16 looks a lot like stacked, slotted wave guides to me.
So...
Here is one for every one to pull apart, it goes beyond every thing I have learnt.
arXiv:1804.10274 [pdf, other]
Lack of time dilation in type Ia supernovae and Gamma-Ray Bursts
David F. Crawford
Comments: 4 pages, 2 figures and 1 table
Subjects: High Energy Astrophysical Phenomena...
Homework Statement
Homework EquationsThe Attempt at a Solution
These AR type problems are mostly tricky and debatable . To me, A is correct and R is wrong . Although electron is approximated to be a point particle , but I think if R is true , then A will be wrong .
I think c) is correct ...
Homework Statement
Homework EquationsThe Attempt at a Solution
These assertion reasoning questions are little tricky . Even simple questions get wrong in a time bound objective test .
In this question I think it should be option b) i.e Both the statements are correct but Statement R is not...
An important step in the evolution of plants, animals, and other complex, multicellular forms of life was eukaryogenesis, the evolution of eukaryotes. Eukaryotes are one of the three major classifications of life (alongside single-celled bacteria and archaea) and are characterized by cellular...
$$\int_{0}^{\pi\over 2}{\ln (2\cos x)\over x^2+\ln^2(2\cos x)}\mathrm dx={\pi\over 4}$$
I am very surprise it has a very simple closed form. I was expecting something else, probably involving a few other constants, like $\ln a$, $\pi$ ...
I don't know how to go about to show that it is...
I have constructed a gain clone type amp based on the LM3886 chip from Texas Instruments. I have wired it using some available 16 gauge stranded wire. It is powered by a centertapped 34 volt (68 volt total) transformer that is fused by a 2 amp fuse. It is working with no issues however I would...
When you have a question that requires you to look at a chart or graph then answer the question using math what are these types of questions called? are they just word problems or is there another name for them? any advice on how I can get better at doing these types of questions ?
Homework Statement
See attached photo
Homework Equations
Stress = F/A
Area = pi d^3 / 4
Sum F h = 0, Sum F v = 0, Sum M = 0
The Attempt at a Solution
Hey everyone, after reading the question a number of times and not knowing for certain where to start, I figured because the stress and area...
I am referring to the output torque of an electric motor when the rotational speed of the rotor is 0 RPM. Some sources say that having a stalled torque damages some motors, and I know that some motors have a constant torque regardless of their speed while others have a max torque at 0 RPM. So If...
Homework Statement
Homework Equations
J = nqvd
J = I/A
Q = It
The Attempt at a Solution
Basically we check whether the variable that we are looking at is proportional or inversely proportional. However, at what part do we stop? Where is it okay to substitute say Q = It and where is it not...
Homework Statement
For example, what type of filter is this:
How can one tell, as a general guideline, without finding the transfer function? I think finding the transfer function is the only real way to tell for sure, but what is a quick way to make an educated guess?
The Attempt at a...
Homework Statement
Identify the type of filter (kinds of frequencies the circuit filters out) analytically
2. The attempt at a solution
I believe the top filter to be an inverting low-pass filter, which passes lower frequencies and blocks higher frequency signals. I also think that the...
I want to build a bass guitar stand for my guitar using wood, I'm modelling it after the image shown. The alterations I'm making are to increase the height of the legs , to place an attachable weight below the stand . This will allow the stand to have a lower center of mass and will greatly...
I have Math Type 6.9 in my computer and everyone of my coworkers has it but there's a problem with mine. Sometimes when I've been working for hours, the math expression I copied from Math Type couldn't get pasted to Microsoft Word (I tried the Save option via Math Type plugin too, and when the...
The attached Image is a for some kind of heat map of temperature with the y-axis corresponding to the time of day and the x-axis corresponding to the time of year. It was generated in Excel from weather data files.
What is this type of data representation called? I've seen the same type of...
Could anyone can tell me how to calculate this type of intergretion. Thanks very much
$$\int\frac{{y}^{3}}{(196 - {y}^{2})\times \sqrt{196 - {y}^{2} - {a + y}^{2}}}$$
To sustain a near perfect vacuum around a computer, that had an outgoing link? Also how would you defuse the temperature and vacuum loss of the outgoing cable to the other circuits? thanks
Already in my mind I envision designing, and to have produced a unique design of boat. I know right now from the get go, that my design is going to be simple, inexpensive, but I am going to give it that which will make it special. I will give it certain features that will make it very...
Homework Statement
MCQS is in the image,
Homework EquationsThe Attempt at a Solution
as the range of this function is the subset of B , it is an injective function ?
option one is correct ?
Okay, so for years the typical mechanism used to describe a white dwarf supernova explosion was that a white dwarf accumulates matter from a main sequence binary companion. Then a few years later, the concept of two white dwarfs crashing into each other came up. With the main sequence companion...
I'm interested in what kind of energy has electric current ?. For everything I taught in school should have kinetic energy because electrons are on a certain potential within the electric field when the switch is closed then the electrons move and the electric current is "generated" which then...
I can't read the tons of posts and replies about one-way light speed in this forum. I was criticised once for sustaining light speed should be equal in both outward and return trips and Einstein's method of syncing clocks as the only reasonable one. Then I studied some scientific articles gently...
There are three geothermal systems that are commonly used: sry steam, flash steam, and binary cycle https://www.eia.gov/energyexplained/index.cfm?page=geothermal_power_plants . What are the efficiencies of the plants from best to least effecient on average?
Hi, I am trying to solve an ODE, however, the initial conditions are not known. From PDE examples, which are quite different, I see that some examples have initial conditions given by functions, and not by constants, i.e::
y(0) = x^2
I may have not modeled the problem correctly yet, however, I...
Probably a very simple question:
Does the coefficient of restitution depend on the collision being performed?
Consider two masses ##m_1## and ##m_2##. They are placed on a frictionless horizontal table and ##m_1## is given an initial velocity, collides 1-dimensionally with ##m_2##, and the...