0

In a scientific paper, the label of the abscissa (the horizontal axis) is "Coordinate x" and it represents the variation in space along the x axis between two points (along the thickness of a sample, where point 0.0 represents one end and point 0.6 represents the other end) of a placeholder function named "Value" (it can be 'Density', 'Conductivity', 'Intensity' etc.) - see attached image.

Example of image that contains the 'Coordinate x' axis label

When referring to it, how is it correct to say?

  1. Variation of Value with coordinate x
  2. Variation of Value with the x-coordinate
  3. Variation of Value along the x-axis
  4. Variation of Value with x
  5. Value with x
  6. Value against x
  7. Value with distance

I've searched and found all expressions somewhat common, with the 3rd example being the most common (although not in scientific context, more about math examples)

What confuses me:

  • When referring to "Coordinate x" or "x-coordinate", one can understand "talking about an actual point of coordinate x" and not "along the axis where the x values are situated", since one can argue that the "coordinate" is a fixed position in space and not an axis label

  • When referring to "x-axis", one can understand the indefinite axis (no start and no end, since its an axis in space), so one might understand that they can attribute values 0 and 0.6 wherever on the axis and talk about the interval between 0 and 0.6 as if it exists wherever in space, wherever they want the origin of their x axis to be (and not where I set it to be)

RobPratt
  • 45,619
Lucian Viorel
  • 13
  • Nice catch, @WeatherVane ! I did edit the question multiple times with the goal to accomodate the people that added comments so that they can add an answer that was most in-tune to their comment (to close the question by accepting the answer). – Lucian Viorel Oct 08 '20 at 14:15
  • 1
    'The graph shows how y varies with x'. The abscissa is called 'the x coordinate'. To give an example, 'This graph shows how the patient's weight varied with age'; 'We graphed/plotted weight against age'. – Edwin Ashworth Oct 08 '20 at 13:21
  • 1
    It is confusing to label the axes "Coordinate X" and "Value". Are they place holders for your real labels, such as "Density" and "Depth"? It is a graph of Value against Coordinate X. It's not made easier by also referring to "Value" as "Variation of Value". Which is it? – Weather Vane Oct 08 '20 at 13:22
  • @WeatherVane , The actual label on the bottom is "Coordinate x" while the label on the left is a placeholder (it can be "Density", "Conductivity" etc.). I edited the question to make this more clear – Lucian Viorel Oct 08 '20 at 13:25
  • @EdwinAshworth , thank you for your comment. I was considering using 'Something varies with x' but assumed it is confusing to say just 'x' in this context. I added variant 4 to the above word-choice. – Lucian Viorel Oct 08 '20 at 13:27
  • All of your examples use "variation". Unless you really are plotting the variation or deviation of some property from an expected value, I would leave it out. As Edwin mentioned, you are plotting Value against Coordinate. – Weather Vane Oct 08 '20 at 13:40
  • Thank you for your comment @WeatherVane ! I have used "Variation of" to describe "how property named Value (which, for example, is the thermal conductivity) changes/varies along the sample thickness -- which is measured along the x axis (the distance between one end of the sample to the other end)". From the feedback I received so far I understand that using "Variation of" is unsuitable in this context, unless I mean how that property changes/varies from an expected value. Am I understanding you correctly? I will edit the word-choice to have an answer without "variation of". – Lucian Viorel Oct 08 '20 at 13:58
  • You keep changing the question as though this site is an interactive tutorial. – Weather Vane Oct 08 '20 at 14:06
  • The graph shows the variation of the density with respect to X. –  Oct 08 '20 at 16:09

2 Answers2

0

If the abscissa (x-axis) shows the distance through your sample and the ordinate (y-axis) shows the density (for example) then you have a graph of density as a function of distance through the sample, or (shorter) density against distance.

Usually the axes are regarded as representing the values shown on them, not the actual distances. Using graph paper allows you to ignore the actual lengthsmore easily.

Peter
  • 1,701
  • Thank you for your answer. I'd like a clarification semi-out of the scope of this question, please. The abscissa is named "Coordinate x" and is the distance through the sample on the Ox plane, not to be confused with the distance through the sample on other planes. So is "Density against distance" correct in this context or is lacking information (since the distance through can be also on Oy or Oz)? I can also say "Density against thickness" since its known to be on Ox, but I'd rather leave the label unchanged and explain the fig. Unless the label itself is wrong (referring to distance on Ox) – Lucian Viorel Oct 08 '20 at 14:57
  • Firstly (not mentioned yet) you need to show the units when you label your axes. There is a big difference between a thickness of 0.6 mm and 0.6 m. Thickness is wrong for the label since it is the distance from one side to the other, which is constant (0.6). You could label it just x, which is standard for distances. Labeling it Coordinate x looks as though it refers to the graph, not to the sample. As suggested in one of the comments above you could also call it depth. Whatever you do need to explain clearly what your terms and symbols and terms are separately, and then be consistent. – Peter Oct 08 '20 at 22:15
0

This discussion has wandered around. Wikipedia gives relevant background information:

The abscissa refers to the horizontal (x) axis and the ordinate refers to the vertical (y) axis of a standard two-dimensional graph. In mathematics, the abscissa (plural abscissae or abscissæ or abscissas) and the ordinate are respectively the first and second coordinates of a point in a coordinate system: Abscissa x-axis (horizontal) coordinate; ordinate y-axis (vertical) coordinate Usually these are the horizontal and vertical coordinates of a point in a two-dimensional rectangular Cartesian coordinate system. An ordered pair consists of two terms – the abscissa (horizontal, usually x) and the ordinate (vertical, usually y) – which define the location of a point in two-dimensional rectangular space.

[Wikipedia]


Your graph shows an example of how the y- and x- coordinates are related when the ordinates are Values (density, intensity, etc) and the abscissae are something labelled "X Coordinate". This labelling of the x-axis is confusing and inappropriate, for the reasons below.

The permissible values of the abscissae (i.e. the permissible values of Distance) are limited to the range 0<=x<=0.6. Corresponding values of y are shown in red.

It is confusing and redundant to label the x-axis as “coordinate X” because x is already understood by convention to be a coordinate. An “actual point” (to use your own term) of “Coordinate X” is really an abscissa with a particular value (of Distance) taken from the permissible range of (0<=x<=0.6 in this case) and should not be confused with the x-axis itself (which notionally extends to infinity in either direction). The x-axis would be far better labelled as “Distance”, which is what you say it is.

If you want to retain the label as "Coordinate X" I suggest that you define it clearly with some statement such as "*where the label Coordinate X is understood as Distance". I see you introduced the notion of 3-dimensionality to the discussion; if you wish to retain the same label in a 3-D discussion, something like "*where the label Coordinate X is understood as Distance in the x-direction" is needed.

The Y-axis is appropriately labelled “Value” (of density, conductivity or whatever you define it to be) and leads to no such confusion.

With this understanding of what the graph means it is conventional to say things such as “the graph shows how density varies with distance”; “the graph shows the variation of conductivity with distance”; “the graph plots intensity against distance”.

Anton
  • 158