What is Parallel: Definition and 1000 Discussions

Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has long been employed in high-performance computing, but has gained broader interest due to the physical constraints preventing frequency scaling. As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors.Parallel computing is closely related to concurrent computing—they are frequently used together, and often conflated, though the two are distinct: it is possible to have parallelism without concurrency (such as bit-level parallelism), and concurrency without parallelism (such as multitasking by time-sharing on a single-core CPU). In parallel computing, a computational task is typically broken down into several, often many, very similar sub-tasks that can be processed independently and whose results are combined afterwards, upon completion. In contrast, in concurrent computing, the various processes often do not address related tasks; when they do, as is typical in distributed computing, the separate tasks may have a varied nature and often require some inter-process communication during execution.
Parallel computers can be roughly classified according to the level at which the hardware supports parallelism, with multi-core and multi-processor computers having multiple processing elements within a single machine, while clusters, MPPs, and grids use multiple computers to work on the same task. Specialized parallel computer architectures are sometimes used alongside traditional processors, for accelerating specific tasks.
In some cases parallelism is transparent to the programmer, such as in bit-level or instruction-level parallelism, but explicitly parallel algorithms, particularly those that use concurrency, are more difficult to write than sequential ones, because concurrency introduces several new classes of potential software bugs, of which race conditions are the most common. Communication and synchronization between the different subtasks are typically some of the greatest obstacles to getting optimal parallel program performance.
A theoretical upper bound on the speed-up of a single program as a result of parallelization is given by Amdahl's law.

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  1. C

    Magnetic Force in Parallel Magnet Setup: Exploring the Strength of Attraction

    Imagine two parallel lines of five magnets each, spaced a few millimeters apart. In the first line, all magnets have their north poles facing one direction. In the second line, each magnet's south pole faces the corresponding north pole of the first line, but the magnets are offset by one along...
  2. A

    B Why is potential difference the same across each branch in parallel?

    As the title says, i am struggling to understand how if the cell is only supplying 3V how 2 lamps in parallel both receive 3 volts (totalling 6) I currently study a level physics and never really questioned how this works and just accepted it as the truth. Can someone explain with a helpful...
  3. Edy56

    Engineering Calculate the power of the coils in this RLC circuit

    So my attempt was I1*jXl1+I2*jXm=I2*(jXl2-jXc2) + I1*jXm because they are parallel so they should have the same voltage. I got I1=-3*I2. I know that J=6-j4 and that J=I1+I2 so I just plugged in what I got and I ended up getting the result for I2 and I1. But they are not correct. Why? I am given...
  4. PhysicsRock

    Why Capacitors in Parallels vs. Series: Coaxial Capacitor Case

    So my idea was to separate the capacitor into two individual ones, one of length ##l - a## filled with a vacuum and one of length ##a## filled with the glass tube. The capacitances then are $$ C_0 = \frac{2 \pi \varepsilon_0 (l-a)}{\displaystyle \ln\left( \frac{r_2}{r_1} \right)} $$ for the...
  5. L

    Calculate Max Resistance for 2 Parallel Wires

    Hi, I am not sure if I have calculated the task here correctly: Based on the drawing, I now assumed that the two resistors are connected in parallel. The total resistance can then be calculated as follows ##\frac{1}{R_T}=\frac{1}{R_1}+\frac{1}{R_2}##. Since the two wires are made of the same...
  6. giodude

    I Quantum Entanglement and Parallel Worlds/Existence

    Hey! I'm new to the forums so its nice to be here. I don't have a deep deep background in physics (I plan to self study after I finish my math studies). However, I recently learned about the notion of quantum entanglement. My basic understanding of it is that quantum entanglement (will use QE...
  7. M

    Finding vectors parallel to a given vector

    For (b) of this problem, The solution is, However, I am confused why the two parallel vectors are ##(\frac{2}{\sqrt{13}}, \frac{3}{\sqrt{13}})## and ## (-\frac{2}{\sqrt{13}}, -\frac{3}{\sqrt{13}}) ## should it not be ##(2,3)## and ##(-2,-3)##. Do somebody please know why they wrote that? Also...
  8. M

    Finding the value of lambda so that two lines are parallel

    For this (ii), The solution is ##\lambda = \frac{4}{3}##, however when I tried solving the problem I did not get their answer. Dose somebody please guide me to their solution and tell me what I did wrong with my method below: ##\textbf {PR} = -3\hat i + 6\hat j - 2\hat k## ##\textbf {RS} =...
  9. yucheng

    Symmetrical parallel inductors, different currents? State Preparation

    We have there parallel inductors (i.e. having the same voltage) with the same inductance, having different currents at a particular time. It appears that this is only possible if the current phasors have different phases See bottom left of video below, ##I_1, I_2, I_3## (time already set to...
  10. Haorong Wu

    MATLAB Can Light Rays Cross Near a BH? - Simulated w/ Matlab

    Hi. I use Matlab to simulate that two parallel light rays pass near a Kerr BH. The angular momentum of the BH points to the ##z## direction. The ##z## components of the start points of the two rays are ## 1\times 10^3 ~\rm{m}## and ##- 1\times 10^3 ~\rm{m}##, respectively. The result, as shown...
  11. Pushoam

    Charge upon a parallel plate capacitor

    a) if I take a Gaussian cylindrical surface whose circular area are present in the meat of the two plates of the capacitor, then the electric flux through this Gaussian surface is zero ( as the electric field inside the meatof the capacitor is zero and between the capacitors, electric field is...
  12. Pushoam

    Capacitance of a parallel plate capacitor with a metal plate kept inside

    Because of the plate P, the capacitor becomes a piece of conductor. It contains zero net charge and has 0 potential difference. Hence, the capacitance is ## \frac 0 0 # # that is undefined. The capacitance of a capacitor is defined as its capacity to store charge when a potential difference is...
  13. K

    How many Parallel Resistive Loads I connect in a 110V branch?

    This is to understand the situation, I'm not going to do this in real world. This is already done in our Cooktops (refer image below). They come with 4 Cook tops with Nichrome heating elements. So my question is, how many Nichrome Heating Elements can be connected in parallel in 110 V socket at...
  14. P

    I Parallel and perpendicular components

    I first tried to use a method based on Gram Schmidt orthogonalization method: $$ v_{\parallel}=\left(v\ldotp\frac{u}{\left\Vert u\right\Vert }\right)\frac{u}{\left\Vert u\right\Vert }+\left(v\ldotp\frac{w}{\left\Vert w\right\Vert }\right)\frac{w}{\left\Vert w\right\Vert }, $$ and $$...
  15. S

    Switching between parallel and series connections (solar)

    We're off grid at 57degrees north. Our source of electricity is solar panels, with a diesel generator as backup. The solar has served us well, until this November, where we had almost 8 weeks of 0 sunshine. I got sick of running the generator. It's noisy, it needs refueling, smells... So I...
  16. V

    Comp Sci Calculating throughput for serial vs parallel

    I know that a serial interface has a single data line whereas a parallel can have several data lines. Could someone check over my work please and thank you. Would it just be, a serial interface: 16 bits x 20 microseconds for 320 bits per microsecond, and then for parallel it would just take 200...
  17. N

    Calculating Input/Output Impedance w/ Parallel Resistors

    Hello, attached are two screenshots showing a common emitter and the same with source voltage removes to find the input impedance. How is it that resistors R1 and RC can be placed in parallel to work out the input and output impedances? Examples i have seen only show straightforward...
  18. A

    Parallel MOSFET safety diagnostics circuit

    I am now faced with a problem. Part of the circuit I'm making consists of a row of many parallel mosfets. Parallel as in the drains are all tied to a rail and the sources also. I wonder, if one of the mosfets goes bad for whatever reason , how could I be able to tell without physically taking...
  19. Lotto

    Can two objects moving parallel relative to a ground meet?

    I think that yes but how to explain it when someone standing on a ground sees them moving paralell? If I move properly, I can see two cars moving paralell ralative to the ground crashing, while someone on the ground do not see them crashing. Is it consistent?
  20. warhammer

    Problem on Parallel Plate Waveguide

    The Imgur Link of the Problem with the figure - Problem Link. I did not paste it here as the post upload quality seemed heavily pixelated for some reason. For this problem, what I did was to divide the waveguide into 2 sections of distinct permabilities to calculate the cutoff frequency. Since...
  21. A

    Bernoulli equation and parallel pipe branch

    Hello! I have a question regarding the application of the bernoulli equation and calculation of the flow through a parallel pipe branch. It's more the basic understanding how the flow will establish. You can find a sketch attached to follow my explanation. Let's assume I have a pipe with...
  22. Shreya

    Capacitor Network - Series or Parallel?

    My textbook solution states that 1 & 2 are in parallel and so is 3 & 4 and those 2 are in series. That is, (1 P 2) S (3 P 4). My thinking is such: points A & B are of same potential, say V, C & D are of same potential, say x and E & F are are of same potential, say 0. So I can say that 1 and 3...
  23. A

    Engineering Resolve Parallel Resistor Error: I Set Rtot = 0.168

    Since the slope of the I versus V graph is equal to 1/R, I set Rtot equal to 0.168. So then I subtracted 1/0.168 by 1/9 and got 1/R1 =5.841. I then found R1 equal to 1/5.841 or 0.171 but it said I was wrong. Can someone tell me what I did wrong?
  24. greg_rack

    Current flowing through resistor in RLC circuit (C in parallel with L)

    Hello guys, LRC circuits with an AC source are having the best over me... had some confusion in class with respect to which method is best using(phasors diagram, reactances or complex impedances) which I am trying to desperately sort out before my exam; here I will show you my best attempt on...
  25. V

    Angular momentum of a disk about an axis parallel to center of mass axis

    I am using the following formula to solve this problem. $$ L_a= L_c + \text { (angular momentum of a particle at C of mass M)}$$ Because the point C is at rest relative to point A, so the second term in RHS of above equation is zero. Hence, the angular momentum about A is same as angular...
  26. P

    Parallel RLC Admittance, Current and Power Vector Diagrams

    (An even longer-winded version was written and deleted out of mercy.) Assume an AC voltage at zero degrees applied to an ideal parallel RLC circuit. For a predominantly inductive circuit, the vector diagram for current should show the supply current in the fourth quadrant (i.e. with lagging...
  27. O

    B Parallel light reflection for a one-way speed of light measurement setup

    Hello, Is there a mirror that will reflect light in parallel trajectories ? If yes, is the reflected light in sync, and will all beams hit a flat surface simultaneously ? Thank you
  28. G

    Four-Bar Parallel Linkage Pendulum

    Hello, I'm new here and I'm looking for advice regarding some calculations of a device I constructed/should construct. It's a 4 bar (parallel) linkage system, which is used like a pendulum. It is released from a certain height, with just the gravity acting on it. I understand how to calculate...
  29. M

    Python Running a for loop in parallel via multiprocessing

    Hi PF! I'm wanting to run a function in parallel, which I've denoted integrate below, on line 33. from math import * from random import * import math, scipy.special import statistics import multiprocessing as mp # READ MATHEAMTICA FUNCTIONS with open("funcL.txt") as fileL: fL =...
  30. guyvsdcsniper

    Method of images between parallel plate capacitor

    Before I can find the force on q I must balance the charges. This problem starts of with -q and q inside the capacitor. I have added image charges on the opposite side of each plate. Would this work?
  31. geochurch

    Should I Disconnect the Onboard B&S Regulator and Use a 10SI Alternator?

    Hi All, hope this is posted in the correct area, we have a Briggs &Stratton motor with a built in charging system, because of additional load a Delco Remy 10SI alternator was fitted to end of the motor to supply additional charging capacity to the battery, any thoughts on this configuration, I...
  32. L

    A disconnected capacitor with two dielectrics in parallel

    I considered the capacitor as two capacitors in parallel, so the total capacitance is ##C=C_1+C_2=\frac{\varepsilon_0\varepsilon_1 (A/2)}{d}+\frac{\varepsilon_0\varepsilon_2 (A/2)}{d}=\frac{\varepsilon_0 A}{2d}(\varepsilon_1+\varepsilon_2).## Since the parallel component of the electric field...
  33. M

    Requesting suggestions for languages, libraries, and architectures for parallel (and sometimes non parallel) numerical and scientific computations

    A lot of the work I am interested to do will be mostly built from scratch by myself, provided there is fair support for numerical types (like complex numbers) and high precision numerical operations (if not, I'll be happy to write those routines as well). Many of my areas of interest are...
  34. Haorong Wu

    I Could a Gaussian beam be described as parallel at a large distance?

    Hello, there. Suppose a Gaussian beam is sent and is received at a great large distance, i.e., the propagation distance ##z \gg z_R## the Rayleigh distance. The Gaussian beam can be described by $$E_0 \frac {1}{w(z)} \exp \left ( \frac {-r^2}{w(z)^2}\right )\exp\left ( -i\left (kz+k\frac...
  35. orochi

    Courses Learning Parallel Computation as a particle physicist

    I am starting my Master's Degree in Nuclear and Particle Physics, should i invest in taking a course in Parallel Computation? I know the role that Parallel Computation has in particle physics, but is there any use in a particle physicst learning about parallel computation, or could it be...
  36. A

    I Parallel Transport of a Tensor: Understand Equation

    According to my book, the equation that should meet a vector ##\mathbf{v}=v^i\mathbf{e}_i## in order to be parallel-transported in a manifold is: ##v_{, j}^{i}+v^{k} \Gamma_{k j}^{i}=0## Where ##v_{, j}^i## stands for ##\partial{v^i}{\partial y^j}##, that is, the partial derivative of the...
  37. V

    Capacitors in parallel or series

    To me it seems like the formula applies to capacitors of any shape or size, since textbooks never mention any limitations on capacitor type when stating these formulae.
  38. P

    I Question about n rotating parallel cylinders

    There are n vertical identical parallel identical cilinders rotating around their length axes with the same angular velocity. The are somehow fixed wrt to Earth and brought together (on a rail?). After the contact there is no slipping and the cilinders are coupled to their neighbor cilinders. It...
  39. KingMan

    Parallel fans in same ducting system

    Currently, I have a mv fan ducted system with two fans in parallel, one duty and standby (each with 7000cmh). If I were to run both fans at the same time, do I get 14000cmh in total?
  40. jackiepollock

    I Why are field lines parallel in a uniform field?

    For a uniform field like this, I imagine the two plates that creates it are made of multiple atoms with charges, which are points sources that create radial fields. We know that radial fields don't have parallel fields lines, so how are parallel fields lines form when the field is made of...
  41. Jrads

    Where Did I Go Wrong in Calculating the Charge's Movement?

    Electric field between the plates V=4x10^3 d=0.02 E=4x10^3/0.02 E=2x10^5 V/m Calculate the force on charge -e -e = -1.602x10^-6 Me = 9.11x10^-31 F=qE F=(1.602x10^-6)(2x10^5) F=0.3204 N Using F=ma a=F/Me a=0.3204/9.11x10^-31 a=3.517x10^29 m/s Time = distance / speed T=.01 (half distance of...
  42. N

    Parallel, Perpendicular, or Neither

    Determine whether the lines are parallel, perpendicular, or neither. Line 1: y = (x/4) − 1 Line 2: y = 4x + 7 Looking at the slopes of the lines, I say neither. Is (1/4) the negative reciprocal of 4? I say no. My answer is neither.
  43. D

    Inductance of Parallel Coils on an uncut toroid magnetic core

    Hi, I have a toroid of a soft magnetic material (any). I wind the complete toroid with single turn coils and connect all their terminals in parallel. Then I wind a second layer of single turn coils on the previous layer and so on. I want to calculate the equivalent inductance L. I calculate it...
  44. meher4real

    Electric field between two parallel plates

    [New poster has been reminded to show their best efforts to work the schoolwork problem when starting a homework thread] My question is : An electron beam with velocity vector v = (0; 0.6x10^8 ;0) m.s enters between two oppositely charged plates parallel to the xz plane. - How large is the...
  45. G

    Optics question: Looking at mirrors from parallel to the surface

    I did a little experiment recently where I took a plane mirror and held it underneath a ceiling light. Then, I began to lower my head so that my view was closer and closer to the surface. When I did this, the image of the light began to drift lower and lower in the mirror until it completely...
  46. cianfa72

    Question about the energy stored in an RLC parallel resonant network

    Hi, I've a doubt about how to the energy is stored in a 'real' RLC parallel resonant network feeds from a sinusoidal source. Take a 'real' RLC parallel network having a resistor ##R_s## in series with the inductor ##L_s## (modeling its loss) with the capacitor C in parallel and consider it in...
  47. A

    3D object parallel projection, filtering of facets

    I'm sorry if the wording is a bit clunky, but this is not a common topic for me. Say you have some 3D object consisting of vertices and facets. There are many tools that can visualize this and they only show its projection on 2D, i.e. on your screen. I presume that you would filter the faces...