In computer science, a for-loop (or simply for loop) is a control flow statement for specifying iteration, which allows code to be executed repeatedly. Various keywords are used to specify this statement: descendants of ALGOL use "for", while descendants of Fortran use "do". There are other possibilities, for example COBOL which uses "PERFORM VARYING".
A for-loop has two parts: a header specifying the iteration, and a body which is executed once per iteration. The header often declares an explicit loop counter or loop variable, which allows the body to know which iteration is being executed. For-loops are typically used when the number of iterations is known before entering the loop. For-loops can be thought of as shorthands for while-loops which increment and test a loop variable.
The name for-loop comes from the word for, which is used as the keyword in many programming languages to introduce a for-loop. The term in English dates to ALGOL 58 and was popularized in the influential later ALGOL 60; it is the direct translation of the earlier German für, used in Superplan (1949–1951) by Heinz Rutishauser, who also was involved in defining ALGOL 58 and ALGOL 60. The loop body is executed "for" the given values of the loop variable, though this is more explicit in the ALGOL version of the statement, in which a list of possible values and/or increments can be specified.
In FORTRAN and PL/I, the keyword DO is used for the same thing and it is called a do-loop; this is different from a do-while loop.
Thanks to @berkeman for the ARRL book recommendation.
While trawling through the theory, I’d like to build an antenna to help cement theory with practice. The receiver is an old valve/tube radio, covering the SW band from 6-18 MHz, or 49-16m.
For simplicity, I thought a small, tuned loop...
From a purely physics point of view, what would be the performance tradeoffs between the following types of shielded H-field pickups or antennas?
Sources:
https://owenduffy.net/blog/?p=18180
https://emcesd.com/tt120100.htm
(A)
(B)...
I separated the circuit into parts- upper and lower
For the upper loop I wrote: -14-2I1-3.4I3-I2 = 0
For the lower loop I wrote 16-2.9I2+3.4I3-5.4I2 = 0
I solved for I1 and I2 separately and plugged it into the junction rule and solved for I3.
I may have got it wrong because of the...
Consider a circular loop with uniform current flowing around it in a uniform magnetic field.
Does it experience no translational force due to its symmetry
I am trying to renormalise the following loop diagram in the Standard Model:
Using the Feynman rules, we can write the amplitude as follows:
$$ \Gamma_f \sim - tr \int \frac{i}{\displaystyle{\not}\ell -m_f}
\frac{i^2}{(\displaystyle{\not}\ell+ \displaystyle{\not}k -m_f)^2}
\frac{d^4 \ell}{(2...
For this problem,
The solution is,
Does someone please know why ##N > 0##. I though at the min speed to still go around the loop, we could set ##N = 0## and ##mg## provides the centripetal force.
Also, I am wondering how to do this problem with using energy conservation.
My working is
## N +...
If a current flowing within a loop is interrupted by a switch a spark occurs at some point which is a result of the built up potential across the opening switch contacts due to the stored energy in the magnetic field that was created by the flowing current.
But what happens if I have a loop...
So I thought I knew how to do this problem but I've run into some issues that make the algebra feel impossible and I am beginning to feel like I'm taking the wrong approach, I ended up rewriting it in a doc because I was concerned maybe my handwriting was the cause of my error so the work is...
Hi All, I have got as far as below, would anyone be able to go over this, I am a little confused with plotting this out onto a graph post equation
Any help would be appreciated, I am hoping to get better understanding before I move onto the next question
4 = 10 (1-e^-t/5)
t = -T in (output...
there are a bunch of problems in this section that ask similar questions, but they ask the amplitude and this doesn't. this is an even problem so i do not have the answer, but my hunch is that it is not an amplitude question. i solved for the amplitude so i am guessing i got this one wrong...
Hi everyone
I've used a game loop to try make a textView alternate between two different strings every two seconds. When I run it, I just get a blank screen. The textView was originally set to show "Hello World!" but not even that shows.
Does anyone know what's gone wrong?
Thanks
public...
Hello,
What I have
I have a NEMA17 stepper motor driven by a DRV8825 driver module, an arduino uno, a multiturn potentiometer.
What I want to do
I want to control the stepper motors in a PID closed loop. The motor shaft will be connected to the potentiometer and I will be sure that the motor...
I got the answer right, but it involved some guessing. So I’m here to make sure I got a conceptual understanding of this.
Normal force is a contact force. If the car was not in contact with the loop (or barely in contact), the loop would exert no normal force on the car. So at the minimum...
Looking to build a suitable closed loop water (probably glycol mix) circulation system to prevent livestock water troughs from freezing. I assume that I need to calculate how much heat loss is predicted from the water tank in ambient air (varies, but assume worst case), then what length of heat...
How can we control the pressure of the water inside a closed loop system (chiller system for example)?
Let´s say, we have a pump curve and an system resistance curve that can be modified (through opening or closing some valves)
In everywhere, what I see is that the intersection of the system...
Hi. I am writing a program in Mathematica that reads a xsl file from excel, then processes it by solving an equation, and lastly turns the processed data into a list for exporting.
Context: Finding the maximum speed of a model plane at different altitudes (density).
Screenshots of the code and...
For those who appreciate boating.
Manitowoc couple completes feat rarer than climbing Mount Everest — boating America's Great Loop, a one year and 6,000-mile journey
https://www.yahoo.com/news/manitowoc-couple-completes-feat-rarer-130503326.html
Great Lakes, Mississippi River, Gulf of Mexico...
In Mathematica, how can we have "M" levels of nested loops, with each loop (level) going from 1 to Counts=##\{N_1, N_2, ... N_M\}## respectively, where the value of M and the elements of Counts are computed beforehand?
I am confused why this is the case, why would it output that number? When I go through the code, there is (x+1)-1 which does equal 1, then x = 2*x is 2? So why is the output not 2? How should I proceed in coming up with a solution? Does this have something to do with cancellation errors somewhere?
From the equation for centripetal force, I can see that the centripetal force is proportional to v^2. Does this have something to do with why there is a normal force at the top? Does the velocity of the object require there to be a normal force? If so, why is that the case?
Setting up the integral to find the flux that is giving me trouble.
I know that I will have to break up this integral into 2 parts, the first part account for when the start of the loop is increasing in area, and another right when I pass the halfway mark of the loop and the area begins to...
Hello everyone,
I would need help to model a motorized system controlled in a closed loop. It is a personal project.
At first, I am looking to obtain the transfer function and simulate the system on computer. In a second step (not the aim of this thread), I would like to use this simulation to...
I am reading a popular-science book Reality Is Not What It Seems by Carlo Rovelli, one of the founders of loop quantum gravity.
He writes:
and
and
So basically, space (spacetime) is just another quantum field like all the others, and the quanta of this field is the nod. Nods have volume...
Hi PFs,
I am reading this paper written by carlo Rovelli:
https://arxiv.org/abs/1010.1939
there are many things that i fail to understand, but i would like to begin with a simple thing.
Rovelli write that:
It is locally Lorentz invariant at each vertex, in the sense that the vertex amplitude...
To solve this problem, we need to evaluate the following integral: $$\epsilon = \int_{P}^{C} (\vec v \times \vec B) \vec dl$$
The main problem is, in fact, how do we arrive at it! I can't see why a Electric field arises at the configuration here. The magnetic field of the rotating sphere is...
##\phi_m = Blwcos\theta##
voltage = ##\frac{-d\phi_m}{dt} = Blwsin\theta\frac{d\theta}{dt}## where l is the length of the loop and w is the width of the loop
The top and bottom of the loop have magnetic forces perpendicular to the loop. My book says that means that there is no current through...
What I have done:
(1) ##\Phi(\vec{B})=\int_{S}\vec{B}\cdot d\vec{S}=-\frac{N\mu_0 il}{2\pi}\int_{s=h}^{s=h+l}\frac{ds}{s}=-\frac{\mu_0iNl}{2\pi}\ln(\frac{h+l}{h})##
so ##\mathcal{E}=-\frac{d\phi(\vec{B})}{dt}=-\frac{\mu_0iNl^2v}{2\pi h(h+l)}## so...
I am confused about this, do the black arrows represent the direction of magnetic force?
The torque ##\tau = -IABsin\theta##, where I = current A is area of loop and B is magnetic field strength and I am a little confused how ##\theta## here is 45 degrees when the angle between the normal for...
I thought the largest PE difference would be when the loop's area vector is in the same direction as the magnetic field, hence cos(0) =1, minus when the loop's area vector in perpendicular to the field, cos(pi/2) = 0. Just plug in the variables and you get 0.126 joules. Did I make a mistake?
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 =...
Hello! I am a bit confused about locking a laser to a stable cavity in practice. I understand there are 2 stages. In the first one you scan the laser frequency and the signal you see on an oscilloscope is made of peaks corresponding to when the laser is on resonance with the cavity. In this step...
I understand that string theory has almost no testable predictions, however loop quantum gravity is an enticing candidate for only quantum gravity and it doesn't explain much of symmetry, constants, mixing angles etc in Standard model. There is obviously not enough evidence to create a full...
Trying to solve for the loop contribution when renormalizing a one loop ##\frac{\lambda}{4!}\phi^4## diagram with two external lines in ##d=4## dimensions. After writing down the Feynman rule I see that:
$$\frac{(-i\lambda)}{2}\int d^4q \frac{i}{q^2-m_{\phi}^2+i\epsilon} $$
But I see no way to...
Which compressed air inlet to a ring (loop) pipeline would likely be best in terms of least turbulance and best flow (avoiding dead head)?
Given:
1) The inlet has to be in the corner of the rectangular loop.
2) Air consumption will be constant and evenly distributed throughout the loop.
3)...
Hello everyone! I tried to solve this problem in a non-inertial system. Probably I should use the principle of conservation of mechanical energy in the following form
$$mgH = \frac{3mgR}{2} + \frac{mV^2}{2}.$$
So the only thing to do is to compute $V^2$. I tried to find this value using the...
I'm just looking at a Bode plot of log(gain) vs log(frequency) for a an amplifier circuit. I'm trying to figure out whether I'm expecting to see a resonance in the gain at the frequency where I measured one. How could I, in principle, work out theoretically where the peak gain should occur - is...
Here is the code that I am talking about-:
n=int(input("Enter a number"))
for num in range(2,n+1):
for i in range(2,num):
if(num%i==0):
break
else:
print(num,end="")
If I give n=5 output should be 2,3,5.
Here is my dry run. Everything is fine except for 2...
Here is the code that I am talking about-:
n=int(input("Enter a number"))
for num in range(2,n+1):
for i in range(2,num):
if(num%i==0):
break
else:
print(num,end="")
If I give n=5 output should be 2,3,5.
Here is my dry run. Everything is fine except for 2...
Summary:: confused in program.
Write a while loop to display each character from a string and if a character is a space, then don’t display it and move to the next character.
Use the if condition with the continue statement to jump to the next iteration. If the current character is space...
Hi all, my work is shown on the attached image. The boxed equation is what I get to but I do not understand how to go from there to what the book has. I am guessing that the problem arises when trying to solve the cross product. I understand that I will need to find the value of the sine of the...
For an opamp in open look configuration,
Here Ad should be equal to open loop gain of opamp and
Now consider the closed loop config of opamp (negative feedback used):
However, Ad is closed loop gain here (according to Sedra Smith) and
In terms of open loop gain,
A is open loop gain...
Hello all!
I am trying to export image0, image1, image2, etc in a for loop. What I have is
For[i = 0, i < 4, i++,
"image" <> ToString[i] =
Rasterize[plfunc3dANGside2[6, 2, 115, 0.1*i], Background -> None,
ImageResolution -> 1000];
Export["/home/josh/ISS_drops/vibrations/" <> "image" <>...
Im trying to obtain regularized (and triangulated) version of Hamiltonian constraint in the LQG. However, one step remains unclear to me.
I am starting with the Euclidean Hamiltonian:$$H_E=\frac{2}{\kappa} \int_\Sigma d^3 x N(x)\epsilon^{abc} \text{Tr}(F_{ab},\{A_c,V\})
$$
Now i have to...
Summary:: Can someone point me to an example solution?
Hello
The attached figure is a four bar link. Each of the four bars has geometry, mass, moment of inertia, etc.
A torque motor drives the first link.
I am looking for an example (a simple solution so I can ground my self before...
Here is the internal circuit of the 741 Op-Amp -
Looking at the output stage, the output impedance seems to be the series combination of ##25 \Omega## and ##50 \Omega##, that is ##75 \Omega##. Is this a qualitative explanation enough to justify the output impedance, or am I wrong somewhere and...
How would you go about calculating the work done in morphing a square current-carrying loop into a circular current-carrying loop, without change in length while maintaining the same angular orientation with an external magnetic field.
My book suggests defining P(potential energy) = M.B (dot...
To be honest I am a bit clueless first with how to interrupt this question I think the bead is going around a wall type thing where there is friction both in the up and X direction. Some hint to get some ideas running would be great