Website Problems

From Phyics 7682 Course Wiki

Report any problems with course website, exercises, hints files, etc.

If you encounter problems with the course web site, such as broken links or inconsistencies with the Hints files, please list them below.

• Missing link to "Percolation Scaling Exercise" in "Percolation Exercises" page in section "Scaling collapses and use of the MultiPlot software"
  • Mission opening anchor tag on line 297
• In the hints file for Intro to Networks, under "def pentagraph()," the first word in the notes should be "pentagraph()" not "testgraph()" (I think). (Yes, you're right. Thanks.)
• In PercolationHints.py, the docstring for PlotPofp() is missing a parenthesis in its definition of standard deviation.
• In MultiPlot.py, the most recent version of matplotlib (not on lab computers, but on personal machines) has pylab.errorbar() returning 3 values instead of 2, causing an unpack error on line 172 when calling MultiPlot with error bars. [cdm89]
  • Workaround: Replace

    line, errorbars = pylab.errorbar(x_scaled, y_sc[cP],
                                     yerr=yerr_sc[cP],
                                     fmt=format)

    with

    line, errorbars, foo = pylab.errorbar(x_scaled, y_sc[cP],
                                          yerr=yerr_sc[cP],
                                          fmt=format)

• In StochasticCellsHints.py, the last line makes a call to "demo()", which is not defined. [cmd89]
• In StochasticCellsHints.py, the docstring suggests using "searchsorted" to find the index where each regular timestep would be inserted, then reading the number of monomers at the preceding index. However, since both "times" and "stochasticTimes" start with t = 0, the default behavior of "searchsorted" will return 0 as the first index, causing the first value of m to be read from the end of the array. [cdm89]
  • Workaround: use "a.searchsorted(b, side='right')" to return indices to the right of equal values. [cdm89]
• In the "Integration Strategies" document (Pendulum Exercise), the text states that τ represents physical time and that t is reserved for a unitless "time." However, it then defines t via the equation , which would give t units of time-squared. If my interpretation is correct, either t and τ should be exchanged, or g and L should be exchanged, in order for this procedure to be dimensionally consistent. [cdm89]
• Typo: in the Pendulum hints file, comment on line 6, "differntial" should be "differential" [gvt3]
• The Pendulum Exercise refers to the function "PendulumEnergyUnit" in step 15 of the "A forward Euler Integrator for the simple pendulum" section. This function does not appear to exist in the hints or solutions files.
• Under "A General Euler Integrator," there a several typos. The function DerivativeArrayFunc is misspelled DerivitiveArrayFunc, and dynamical is spelled dymanical on the second bullet. [yc362]
• On the Pendulum Exercises page, equations are hard to read due to JPEG compression (in particular, the upper integration bound in finding the period. also note faintness of fraction bars). Save directly to PNG instead (lossless compression, and should be smaller in filesize too) (hint: generate images using wiki). [cdm89]
• On Pendulum Exercises page, under computing the period, should be , not ω = − sin(θ).
• Log-Log plots in MultiPlot() in MultiPlot.py are strange. In line and symbol plots, not all the symbols are connected by lines. Here is an example:
  • I think this happens when the "missing points" have a y-value of 0 and cannot be plotted on a log scale, but I'm not sure

• Minor typo in Pendulum Exercises: under "The Period of the Pendulum", I think "keep repeating until theta changes time" should be "keep repeating until theta changes sign". [cdm]
• Solution to def SimulateElectionFromPolls(evotes, polls, date): has an error: it should read "for state, dem_win in dem_win_probs.items():", not "for state, dem_win in polls[date].items():" [yc362]
• The server may be down, I'll check back later. (In the Pendulum Exercise procedure, the link to the pylab tutorial leads to a page error.)
• In the Pendulum Exercise hints file, the mass should be mentioned as a parameter of the function PendulumEnergy. That is, the hints for this function should include mass=1 along with length = 1 and g = 1, for clarity.
• In ChaosLyapunovHints.py, the meaning of the parameter tuple 'p' is inconsistent. In one function it is (lyapExponent, lyapLogPrefactor), while in others it is (lyapExponent, lyapPrefactor). For these functions to be used together, should the definitions be compatible? [cdm89]
• On the Double Pendulum Exercises page, part #9, second bullet point, in the sample DoublePendulumTrajectory() call, "initialomega2=0.2" should be "initial_omega2=0.2". (gvt3)