Graphmatica Bug reports

Past bugs

• y=int x does not finish graphing

  Symptom: The entire graph is drawn, but the program stays in "graph" mode.
  Cause: A change avoid missing steep, narrow lobes of polynomials by detecting changes from positive to negative slope was unintentionally catching graphs with zero slope as well.
  Workaround: Abort graphing manually once it is done.
  Status: Fixed in version 2.0.

• Errors in second order ODE examples file

  Symptom: Two equations in the demo file ODE2.GR are incorrect (or the comment on them is incorrect, depending on your point of view).
  Cause: I was not paying attention and neglected a factor of two in the formula for simple harmonic motion.
  Workaround: You can download the corrected ODE2.GR here.
  Status: Fixed in version 2.0.

• Problems with families of curves when decimal separator is ","

  Symptom: After drawing the first graph in the family, the program stops with the error "Your equation included a variable or function that Graphmatica does not support, or you mis-typed a function name. Please edit your equation and try again."
  Reported:2/16/00
  Cause: When the decimal separator is set to "," the parser becomes confused unless you add spaces between the terms in a domain. Unfortunately, when the program defines the variable "a" for you, it does not do this.
  Workaround: Specify the domain for "a" by hand like so "{a:1, 5, 2}".
  Status: Fixed in French version 1.60e and in version 2.0.

• Flow fields drawn incorrectly for non-square grids

  Symptom:The program draws too many or too few slope vectors in the vertical dimension.
  Reported:2/9/00
  Cause: The flow field graphing code was unprepared for a non-square aspect ratio.
  Workaround: Square up the grid.
  Status: Fixed in version 2.0.

• Program crashes when choosing Redraw/Last Graph menu item

  Symptom:Choosing Redraw/Last Graph when there are no graphs crashes the prorgam.
  Cause:That is not really a valid time to be using that menu item.
  Workaround: Don't do that.
  Status: Fixed in version 2.0.

• Multiple unary minus signs handled incorrectly

  Symptom: y=--x graphed the same as y=-x.
  Cause: There was a bug in the code to scan negative numbers.
  Workaround: Don't enter silly equations like y=--x.
  Status: Fixed in verison 1.60e.

• Very small domain not respected in log-log graphing

  Symptom: Plotting a function with a domain with a small (much less than 1) endpoint on a logarithmic scale will often plot past the upper bound of the domain.
  Cause: The margin of error for the calculation to determine whether the function is within the bounds of the domain is not being adjusted properly to account for the logarithmic step rate.
  Workaround: None available.
  Status: Fixed in verison 1.60e.

• Set Domain feature may leave extraneous "x" or "y" in equation

  Symptom: After using the Point Evaluate or Critical Points dialog box, using the Set Domain function to select a new domain using the mouse will put an "x" or "y" in between the equation and domain instead of a space.
  Cause: Temporary variables in these dialog boxes were improperly assigned the same memory as the constant string for a single space, and overwriting it.
  Workaround: Enter the domain manually, or edit the equation to remove the offending character.
  Status: Fixed in verison 1.60d.

• Polar/parametric graphs not back-tracking properly when first on-screen point graphed

  Symptom: For example, some of the segments in r = a(pi - t) {a: - 15, 15, .12} stop short of the top/bottom of the screen. (This bug does not affect Cartesian graphs.)
  Cause: When the first part of the domain for a function is not visible on screen, the program is designed to scan forwards quickly until it finds an on-screen point, and then back-track if necessary to the first point in the domain which is visible. However, unwanted interaction between the back-tracking and automatic fineness adjustment code was causing the back-tracking to stop prematurely when the fineness had to be increased quite a bit to get a point close enough to the first to draw a smooth graph
  Status: Fixed in verison 1.60d.

• Graphs of odd powers of y only draw the positive half of the function

  Symptom: For example, x=y^3 only draws graph for x > zero.
  Cause: When isolating y in equations like this I neglected to check whether the resulting fractional power of x was odd or even, and therefore conservatively assume that it is even and therefore not defined for x < 0
  Workaround: Isolate y by hand (y=x^1/3) or add another term with y in it to force the equation to be evaluated as a function of y, not x (x=y^3 + 0y)
  Status: Fixed in verison 1.60d.

• Integrate curve shades wrong side of curve in certain zoomed-in situations

  Symptom: When finding the area under a curve, and the x axis is not on screen, Integrate curve may shade the area between the curve and infinity instead of between the curve and the axis.
  Cause: The calculation of the physical coordinate for y=0 can overflow if the axis is too far away from the edge of the screen, causing it to have the wrong sign.
  Workaround: Don't zoom in so far that the x axis goes off the screen when displaying integration regions.
  Status: Fixed in verison 1.60d.

• Edge of screen not handled correctly for "vertical" graphs

  Symptom: Vertical lines (x=n) missing several pixels at top of screen; inequalities like x > n may not fill correctly
  Cause: The graph loop for these equations is exiting prematurely before the last several pixels have been calculated.
  Workaround: As above, you may be able to obtain the correct fill behavior by resizing the window slightly.
  Status: Fixed in patch release 1.60c.

• Integrate curve does not handle large, off-screen regions properly

  Symptom: Program may crash when drawing integration region where most of the region is not visible on the screen
  Cause: The calculation for the number of points required in the region to shade was exceeding the maximum allowed and wrapping around to negative numbers, causing invalid memory allocation.
  Workaround: Only integrate over a range which is completely visible on-screen.
  Status: Fixed in patch release 1.60c.

• [Windows only] Copy graphs (WMF format) contains unwanted raster data

  Symptom: Importing metafiles from Graphmatica into AutoCad fails with message "Raster data in the metafile has been ignored"
  Cause: An operation to clear the drawing surface for bitmap copy was incorrectly included in the metafile copy as well.
  Workaround: Unknown.
  Status: Fixed in patch release 1.60c.

• [Windows only] Default fonts not TrueType in low-resolution modes

  Symptom: Side labels are not rotated properly, or text is not scaled correctly when printed.
  Cause: When running in less than 1024x768 resolution, the program selects "Courier" instead of "Courier New" as the default font for grid text and labels. This is a screen font and may not scale or rotate properly like a TrueType font.
  Workaround: Select any font you wish for the affected text using the Fonts dialog box (View menu). Then Save Setup Info from the file menu to make this selection the new default. Graphmatica will only let you choose TrueType fonts when you select a font manually so any choice is OK.
  Status: Fixed in verison 1.60a.

• [Windows 95 only] Mouse capture not released when switching to another application

  Symptom: If you switch to another application while in the coordinate cursor, or in domain/tangent line/integral selection mode, the mouse pointer continues to be restricted to the borders of the current grid in Graphmatica.
  Cause: Historically, there has never been any code to handle this scenario, because it was impossible to encounter (in Windows 3.1, you cannot switch applications using Alt+Tab when mouse capture is on).
  Workaround: Switch back to Graphmatica and click on the grid to exit the coordinate cursor or other feature which invoked the mouse capture.
  Status: Fixed in verison 1.60a.

• Point tables may erroneously show values where function not defined

  Symptom: At fractional intervals between points, the point tables may show a value for discontinuous functions like y=(x^2-2)/(x-1) at the point of the discontinuity. They should show "Error" where the function is not defined.
  Cause: Due to normal roundoff error the point calculated was actually not precisely at the singularity, so the function really was defined. However, this is disguised by the fact that the value of the independent variable is rounded back to the precise value of the singularity when it is printed.
  Workaround: Zoom out. Rounding error is not usually significant when the interval between points in the table is an integer value.
  Status: Fixed in verison 1.60a.

• [Windows only] Cannot position annotations with the keyboard

  Symptom: When placing annotations, the arrow keys have no effect.
  Cause: The keyboard focus is not being set properly to the graph window.
  Workaround: You must place annotations using the mouse.
  Status: Fixed in verison 1.60a.

• [Windows 95 only] Toolbar buttons overlap equation editor when IE 4.0 installed

  Symptom: See picture.
  Cause: Internet Explorer 4.0 surreptitiously "upgrades" some system DLL(s) with versions that appear to be incompatible with programs built to use the original toolbar controls. In particular, the toolbar seems to require an explicit resize message before I can calculate its size correctly in order to position the editor window properly.
  Workaround: Avoid or un-install IE4.
  Status: Sort-of fixed in verison 1.60a. But it appears that Microsoft has fought back with yet another new version of the toolbar control, which still makes space on the buttons for unwanted text unless I add an API call which didn't exist in the original version of this control. Sheesh. But I think I have this fixed for real in version 1.60e.

• [Windows only] Polar graph paper with gridlines is broken

  Symptom: Polar graph paper displays as a single "blob" when you have selected gridlines or solid gridlines detail level
  Cause: I seem to have broken this when I modified the way the way graph paper is drawn when you have selected "dots" detail level so that the dots scale to a reasonable size when printed. This is causing the ellipses which are drawn for polar paper to be filled rather than outlined.
  Workaround: Select the Dots detail level when using polar graph paper.
  Status: Fixed in verison 1.60a.