![]() It’s from the more obscure De Practica Geometrie.īut is his use of “abscissa” the same as ours? Here’s two excerpts: The use of the word isn’t from his most famous book, Liber Abaci (of the rabbits and the series that bears his name). Also, some dictionaries seem to be picking Leibniz as the first to use abscissa however he was simply the first to popularize it. And a Professor Barney Hughes (from the Pat Ballew entry) claims 1220.įor the later dates, the dictionaries might be aiming for the first use in English, even though the word is identical in Latin. Merriam-Webster claims the first use was in 1694. The Online Etymology Dictionary claims the first use of the word was 1698. In other words: “a line cut off from another line”, rather like the Merriam-Webster picture above. Going deeper, “ab-” means “off” or “away” (as in abnormal) and “scindere” means “to cut” (as in re scind). It’s Latin, from “linea abscissa”, meaning “a line cut off”. None seem to have much of anything to do with the x-axis. There’s also an abscissa of stability and an abscissa mapping and a spectral abscissa. The definition avoids the confusion from the standard dictionaries (and even avoids the Cartesian nitpick), but tosses in an extra use: abscissa as the x-axis itself.įor example, here’s an excerpt from On the Relative Abundance of Bird Species:įor convenience, the abscissa is graduated logarithmically. Physicists and astronomers sometimes use the term to refer to the axis itself instead of the distance along it. The x-(horizontal) coordinate of a point in a two dimensional coordinate system. Just to nitpick, the abscissa also applies to oblique coordinates, not just Cartesian ones.īut that’s not all! Try this version of the definition from MathWorld: The impression is so strong to me I am left wondering if there the word has ever been used historically in such a way. That is, (5,3) would give an abscissa of 5 and (-5,3) would also give an abscissa of 5. The definitions give the impression that the abscissa is the unsigned value of x. Not sure where the confusion is yet? Try this picture from Merriam-Webster: The horizontal coordinate of a point in a plane Cartesian coordinate system obtained by measuring parallel to the x-axis. (in plane Cartesian coordinates) the x-coordinate of a point: its distance from the y-axis measured parallel to the x-axis. Since it’s also in the As (before dictionary writers get tired) there shouldn’t be any ambiguity, issue, or controversy. (The y value is called the ordinate, which in the example would be 5.) * For example, the abscissa of (-3,5) is -3. However, if their ordinates are negative then the straight line lies below the x-axis and at a distance equal to the magnitude of the common ordinate (here 6 as magnitude of (-6) is 6 irrespective of sign]).In a (x,y) coordinate system, the abscissa is the x value. If their ordinates are positive then the straight line lies above the x-axis and at a distance equal to the common ordinate (here 6). Their ordinate determines how far the straight line is from the x-axis. If two points have equal ordinates then they lie on a straight line parallel to the x-axis. However, if their abscissae are negative then the straight line lies on the left side of y-axis and at a distance equal to the magnitude of the common abscissae (here 4 as magnitude of (-4) is 4 irrespective of sign]). If their abscissae are positive then the straight line lies on the right side of y-axis and at a distance equal to the common abscissa (here 4). Their abscissa determines how far the straight line is from the y-axis. If two points have equal abscissae then they lie on a straight line parallel to the y-axis. You can put this solution on YOUR website!
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