What is Error: Definition and 999 Discussions

An error (from the Latin error, meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake.
In statistics, "error" refers to the difference between the value which has been computed and the correct value. An error could result in failure or in a deviation from the intended performance or behavior.

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  1. S

    Relative error of radius when derived from diameter

    Hi guys Have lurked the forums for a while but this is my first contribution. I am in first year physics at uni and I was having a discussion with my tutor regarding the relative error for an experiment (circular motion / moment of inertia). (I tried searching for an answer to this with no...
  2. Z

    Error in Bel's 1958 Article: Correcting Lanczos Formula

    hey all, in this link :http://gallica.bnf.fr/ark:/12148/bpt6k7258/f122.image The equation 2b is not correct I believe. Please correct me if I'm wrong. Here we go : The equation mentioned reads : Rαβλμ Rαβλρ = 2 * 1/8 * Rαβλμ Rαβλμ gμρ Now multiply out by gμρ on both sides and elevate the μ...
  3. A

    Fortran Troubleshooting Function Call Error in Subroutine

    So I am making a module to run in the main program. The module contains a subroutine and several functions. I want to call one of the functions into the subroutine but it is not getting recognized. I am just doing Real :: fct %fct is the function name that returns a real value but when...
  4. R

    Error Bounds for derivative estimation

    So we are estimated derivatives using a three point formula in class and the giving bounds for the error. I was given a table of x1=1.1, x2=1.2, x3=1.3, x4=1.4. I have to find an error bound to estimate the error for x=1.1 and 1.3 for f(x)=ex In class we did x=1.1 as follows...
  5. Darth Frodo

    G by free fall experimental error

    This isn't so much a H/W question, but we have 2 sets of values, TMax and Tmin. Δ is the difference between them. We are told to get Δ/2 and get the %uncertainty of this. Why do we halve Δ?
  6. H

    MHB How Accurate is Lagrange Interpolation for Approximating Cos(0.75)?

    Problem: Use the Lagrange interpolating polynomial of degree three or less and four digit chopping arithmetic to approximate cos(.750) using the following values. Find an error bound for the approximation. cos(.6980) = 0.7661 cos(.7330) = 0.7432 cos(.7680) = 0.7193 cos(.8030) = 0.6946 The...
  7. Y

    Finding Active & Reactive Power: Possible Error in Lecture

    here is a screenshot from one of my lectures talking about how to find active power (P) and reactive power (Q) He calculates P using 100*10 Cos (30-(-30), which I understand, though the answer he gets is 200W, but whenever I calculate it I get 500 because cos60 = 0.5 and 0.5*1000 is 500...
  8. A

    Definition of relative error

    Hi all, I have a general question about relative error. Suppose that we have a vector of measurements \hat{b}=\left(\hat{b_{1}},\hat{b_{2}},...,\hat{b_{n}}\right). Furthermore, suppose that these measurements are accurate to 10%. My natural interpretation of this statement is that there is...
  9. F

    Calculating distance (and percent error) using parallax

    Hi all, This is a homework problem, but I don't think asking for help here presents any ethical issues. I'm permitted to consult my classmates and compare solutions with them as long as I do my own work, and I plan to ask my professor for help if I still feel unsure after reading your...
  10. M

    Error Analysis and Simpson's Rule to approximate integrals

    Hey there, This isn't exactly a homework question, but my question did arise while doing homework and I wouldn't know where else to post it, so here I am. I'm a Calc 2 student and covered approximations of integrals that I normally wouldn't be able to integrate today. I was going through the...
  11. L

    Why is the factor of 2 present in the expression for loss?

    Hi Guys, I am just starting readings on machine learning and came across ways that the error can be used to learn the target function. The way I understand it, Error: e = f(\vec{x}) - y* Loss: L(\vec{x}) = \frac{( f(\vec{x}) - y* )^2}{2} Empirical Risk: R(f) = \sum_{i=o}^{m} \frac{(...
  12. S

    Illegal Instruction Error in Mac terminal

    I am running a mac os x 10.7 system I am writing a fortran code which compiles, however, whenever I run my code (./file.out) all I receive in return is the message "Illegal Instruction". I have tried messing with my code and I continue to receive this message. Any help with this would be...
  13. B

    Problems with propagation of error for multiple variables

    please help by telling me whether my approach to solve the problems are right or wrong. please refer to the ATTACHMENT for the questions and my approaches... your help is highly appreciated!
  14. B

    MHB Problems with propagation of error

    I have problem regarding the propagation of error since the equations involving mixtures of multiplication, division, addition, subtraction, and powers. Please help me to clarify whether my attempts are right or wrong.
  15. B

    Problems with propagation of error

    Homework Statement I have problem regarding the propagation of error since the equation involve mixtures of multiplication, division, addition, subtraction, and powers. Please help me to clarify whether my attempts are right or wrong. Your help is highly appreciated. Thank you. PLEASE REFER...
  16. M

    Mathematica MaxRecursion(/WorkingPrecision?) Error in Mathematica 8

    I'm getting an error message that suggests my attempts to increase the variable MaxRecursion in NIntegrate aren't working. I define f[n_,b_]:=NIntegrate[q*BesselJ[0,q*b]*(-(2/(n (2+n) q^4))+(1-q^2)^(n/2) HeavisideTheta[1-q^2] ((2+n q^2)/(n (2+n)...
  17. T

    Error incurred from approximating fermi surfaces to be a sphere

    I read somewhere that the error incurred from approximating the Fermi surface to be a sphere in k-space goes as 1/N where N is the number of electrons. So, N is generally of the order 10^23. I couldn't figure out how they came up with the value. I was trying to say that the actual shape of the...
  18. J

    Proof Error Q. Conway's Functions of One Complex Variable VI

    I ask this question only to those who read or have this book: If you have Baby Rudin, it would be even better. On the page 34 of the text Conway's Functions of One Complex Variable Vol 1, it proves the Chain Rule but it seems the proof is not valid: It uses sequences to show the limit is...
  19. G

    Acres to miles: conversion problem (book error?)

    Homework Statement Problem 2.2 An acre is defined such that 640 acres = 1 mi2. How many square meters are in 1 acre? Homework Equations Solution From Table 2.1, 1 mi = 1.609 km = 1609 m 1 acre = 1/640 mi ^2 The Attempt at a Solution My solution comes from wolfram alpha 4286 m^2 BOOK...
  20. S

    Physics help please - Sources of error in lab experiments

    Physics help please -- Sources of error in lab experiments Ok so i need some help with a few labs.. some I've tried out and a few i just can't get.. what i want to know is whether the limitations and sources of errors that i wrote down for each of these labs are correct or not and what i could...
  21. G

    Error in numerical approximation of an integration

    Homework Statement a,b\in R, a<b, n\in N\\ h=\frac{b-a}{n} , x_i = a+ih , i=0..n \\ f\in C^1[a,b] we approximate the integral of f in a,b with Q_n(f) = h\left[f(x_1) + f(x_1) + ... + f(x_n)\right] Find the error R_n(f) = \int_a^bf(x)dx - Q_n(f), as function of the first derivative of f...
  22. Z

    Calculating Standard Error of Mean for 2D Histogram Data

    Hey everyone, I'm not sure if there is an effective answer to my problem, but here goes: I am working on Ramachandran plots for short peptides (3 amino acids long). For every snapshot of the protein (this would be my data point) there are two angles being recorded, the phi and psi angles...
  23. G

    Measuring error analysis with 3 variables

    Homework Statement Consider the function F(xyz)=x^4+5y^4+2yz+3. Let the uncertainty in x be represented by the variable dx, the uncertainty in y be represented by the variable dy, and the uncertainty in z be represented by the variable dz. Find an algebraic expression for the uncertainty in...
  24. C

    Prediction error in a random sample

    I have an exercise that I do not understand how to solve (statistics and probability is really my weaker part...). The exercise goes as follow: In a certain population, the random variable Y has variance equal to 490. Two independent random samples, each of size 20, are drawn. The first...
  25. R

    Center of mass of a solid hemisphere (where's the error)?

    On finding the center of mass of a solid hemisphere i came up with some different result. Here's what i did... consider a small ring at a distance r from the center of the hemisphere and one more ring at a distance of r+dr from center of the ring. let, mass of the small element formed...
  26. S

    Can anyone confirm this possible error in 'Vector Calculus' by Matthews?

    Homework Statement Find the surface integral of u dot n over S where S is the part of the surface z = x + y2 with z<0 and x>-1, u is the vector field u = (2y+x,-1,0) and n has a negative z component. Homework Equations In the text leading up to the end-of-chapter exercises (where this...
  27. W

    Proving PMI from nothing? Help find the error

    "Proving" PMI from... nothing? Help find the error! Homework Statement Prove the Principle of Mathematical Induction from the Well-Ordering Principle. Homework Equations Principle of Mathematical Induction (PMI): If A \subset \mathbb{N} satisfies (i) 1 \in A, (ii) if k \in A, then...
  28. S

    Error in Young/Freedman 13th? (Integral)

    In chapter 5 of Young/Freedman's University Physics, 13th ed., Eq. 5.10 is given as: ##v_{y} = v_{t}(1 - e^{-\frac{k}{m}t})##, where v_{y} is the time-dependent speed in the vertical direction of a low-mass, slow-moving object falling through a fluid, and ##v_{t}##, ##k##, and ##m## are all...
  29. L

    Statistics - Standard Deviation, Standard Error and Mean

    Hello, Just had a question regarding statistical analysis. I'm trying to calculate the average of 4 numbers from a data set of 6 numbers in excel without manually choosing to average only the 4 numbers. e.g. 85 20 32 45 27 3 (total mean = 35.3 desired mean = 31) 100 30 27 40 21 1...
  30. Hepth

    Error propagation with two functions, two unknowns.

    If I have two independent variables x,y, and two measurements, m1, m2 with errors. And the dependence is thus: m_1 \pm \delta m_1 = f[x,y] m_2 \pm \delta m_2 = g[x,y] Now in my case, f and g are complicated expressions of x and y with no simple solution. (Actually I think i can...
  31. clope023

    Python Vector Class no attribute error

    Hello all, my issue is in calling the attributes of a 3d vector class in python, this is the class I was working with: import math class Vec3: ''' A three dimensional vector ''' def __init__(self, v_x=0, v_y=0, v_z=0): self.set( v_x, v_y, v_z ) def set(self, v_x=0...
  32. A

    Wikipedia error about the complementary error function?

    Take a trip over here and explain to me what is meant by taking the double factorial of -1. If you try to let N = 1 in the remainder formula, you wind up having to take (2(0) - 1)! = (-1)!, right? This strikes me as a typo; should it be changed? If so, to what?
  33. T

    Fortran New to FORTRAN, Error message I don't understand

    Hi! I am completely new to Fortran and I'm trying to compile a source code someone else has written. I get the following error: [Error] TESTEPH.F(187); type mismatch: intg JPLEPH assigned to char*80 NAMFIL. The code around line 187: 183 C NAMFIL IS THE EXTERNAL NAME OF THE BINARY...
  34. W

    Error in Algebraic Construction or Computational Translation?

    I have an equation that I've been trying to solve. I manipulated it until I had a=f(d) and then did by best to put it into a format the computer recognizes. However when I went back to check the results against the unsimplified version of the equation, they didn't work out as they should have...
  35. H

    Does the use of error bars pertain to this experiment?

    I'm currently performing a real bench experiment that would essentially validate the results of those generated in two different computer models. Essentially, there is one (real) test setup, one computer model, and another (but different) computer model. I have ONE result from each of the...
  36. H

    Optimizing Soft Error Pulse Width for CPU Fault Injection

    Homework Statement Hi, I am trying to inject some faults into a CPU manually. But I am not sure what should the soft error (SET) pulse width should be? I know that is different in different case. Therefore, I am going to set up a random generator to generator the SET pulse width. But what range...
  37. A

    Improving propagation of error in successive calculations

    Hi, When using data in calculations, errors can be introduced by the calculations themselves; A common example of this kind of data is the atomic mass of some element; The data might be reported by NIST as: 190.233(20), which indicates that the mean is 190.233, and the maximum likelihood...
  38. Y

    [Fortrran] Some help with a code error: Segmentation Fault

    Hi, I am having a segmentation fault error just when I ask the code to print the value ipos in the program. However, If I change the print to the module, the segmentation fault does not appear. Could anyone can help know, why I can not transfer the variable ipos from the module to the main...
  39. P

    Cadense Orcad 16.3 Error D_D1 is undefined

    Cadense Orcad 16.3 "Error... D_D1 is undefined" I designed a half wave rectifier circuit using resistor, Vsin and 1N4148 diode with the aid of Cadense Orcad 16.3 version. However, after running the simulation, I got an error message saying that the part D_D1 is undefined. I looked for the...
  40. N

    Ansys Workbench- Max Principal Stress Error

    Hi all, I did simple problem, in which assembly is subjected to single load & it is fixed at other end. I used Higher Order Tet element (& tried with Hexdominent Method also) for the casting body. The vonmises stress shows the true results but when i was looking for the Max Principal...
  41. S

    Statistics question: error of slope in linear regression from r

    A text says that if you calculate the linear regression of data points and you get the equation y=mx+b with an r2 value, the error in the slope is given by: δm/m=2(1-r) No explanation was given. Could someone please explain this formula? Thanks!
  42. A

    Solve for 0<b<a: Proving Inequality & Approximation Error

    Homework Statement Firstly, I'd just like to point out that this is not actually a course related question. I have been trying to teach myself mathematics, and have been grappling with this for a couple of days. The book has no answer at the back for this particular question. Variables...
  43. M

    Troubleshooting C Code: Segmentation Fault in GCC on Ubuntu

    the following code #include<stdio.h> #include<stdlib.h> int main (int argc, char *argv[]) { int* a; *a=1; return 0; } compiles ok, but throws "Segmentation fault (core dumped)" at runtime why is that? i'm working with gcc in ubuntu. I have been able to compile and run...
  44. sunrah

    Error propagation for value not directly measurable

    Homework Statement This should be very simple: Given the following (boundary frequency for photoelectric effect): \nu = \frac{\phi}{h} what would be the error on \nu? Homework Equations The Attempt at a Solution \varphi and h are both determined through linear regression (y = mx + c). Where...
  45. S

    Fortran Error when reading list, Fortran 77

    Hello, I'm trying to run a simulation program, written in Fortran 77 for the g77 compiler ( I use gcc version 3.4.6). I get the following error message when running the program: invalid number: incomprehensible list input apparent state: unit 3 named combin.fig last format: list io...
  46. P

    Evaluating a log by trial and error

    Hi, I'm evaluating a log, and I'm wondering how many words I can use. When I'm trying different exponents to narrow in on the exponent that I'm looking for, can I use words next to each equation? For example, "this is not big enough" next to the numbers that aren't close to the number I'm...
  47. P

    Numerical integration of the ERROR in a PI controller

    good day all.i've just written a program in fortran77 for the model of a binary distillation column.i included a PI controller in my program.To obtain the integral term of the PI,I used the explicit euler to numerically integrate the error.i would love to compare my results using another method...
  48. S

    P-Controller Design for Steady State Error

    Homework Statement So this is a bit of a two-part question and I'm unsure which part I'm not doing right (or both!). i) Find the closed loop transfer function of the system shown ii) Design a proportional controller for the system to give a 10% steady state error Any help, hints, suggestions...
  49. J

    The precision of the argument function error message, graph not plotted

    "The precision of the argument function" error message, graph not plotted I've got a function, integratedadvthirdaltb, that I'm trying to use in plotting some graphs: thirdaltb[KP_, Ps_, C_, M_] := NSolve[Sqrt[2*M]*b + InverseCDF[NormalDistribution[0, 1], Ps]*...
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