How does the word "spline" mean curved (and why not just use the word curved)?

In mathematics a splines form a special class of functions used to fit a curve to a series of points. I've used them to create calibration curves from experimental data, although eventually I decided that cubics, fitted to four adjacent points, to be more useful than splines.

Any good drawing software will have a way to fit splines to produce a smooth-looking curve from a set of points. In that situation you're probably not fitting to experimentally obtained points, but rather moving the points around until you get a suitably attractive curve.

In the days before computers, draughtsmen created splines with the aid of a flexible ruler.

I've never heard "spline" used to mean an arrow, but I suppose you can always tack an arrowhead onto the end of a curved line.

"Leader" is presumably a term of art that I haven't met.

Does "spline" mean something else to you?

Specifically, as I understand it, they're sections of polynomials fitted together smoothly. (Hey, I said "fitted".)

In fact, according to the Oxford English Dictionary, "spline" was originally East Anglian dialect for "A long, narrow, and relatively thin piece or strip of wood, metal, etc.; a slat."

Me neither. I know it only as a row of dots that connects, say, a chapter title with a page number in a table of contents.

In woodworking, a spline is a long (and perforce rigid) bar of material used to join two grooved work pieces (essentially acting as a two-sided "tongue"), running cross-grain and providing greater strength than a simple butt joint by greatly increasing glue surface area. I suspect the same sense exists in metalworking as well.

-GAWollman

Garrett Wollman wrote, on Mon, 06 Oct 2014 04:50:01 +0000:

With that as a starting point, I find the woodworking use of "spline" here.

I wonder if the woodworkers know that a "spline" means a curved line?

I didn't read everything above.. but maybe the use of spline by woodworkers is more closely related to the "splint"--like you would use on a broken finger.

How about this--to "spline", to smooth or set straight. Everybody happy? ; )

Bill

Bill wrote, on Mon, 06 Oct 2014 02:08:32 -0400:

That might explain why the woodworker's "spline" is straight, while the draftsman's spline is decidedly curved!

I wonder how a woodworking draftsman handles the confusion when he has to draw a draftsman's splined leader to a woodworking spline?

If this a problem for him, then he should sort nails: The nails to use on the east side of the house in one pile, and those for the west side of his house in another pile. The latter was the sort of the punch line to a joke that went around last week or so.

A spline, in caning chairs, etal., is a "reed" used to hold cane in place, as with pressed in cane. It's flexible, so it can be installed in/on strai ght and curved grooves/runs. A caning spline is usually seen, once install ed, so it is part of the "decor" of the caned application.

Sonny

Garrett Wollman wrote, on Mon, 06 Oct 2014 04:50:01 +0000:

In the boat-building craft, a spline is a long thin strip of wood with very uniform bending characteristics. It's used in a process called lofting.

In the days before computers did all this, the designer produced a table called a table of offsets, and the builder laid out the lines of the boat full-size on a large flat surface (often in the loft of the boat shop, hence the term lofting). The boat builder laid out the coordinates of points on the surface from the table of offsets, and then used the spline to fair the lines of the boat into fair curves. The builder would try to locate the spline so that it ran through all the points, holding it down in place with weights called ducks (hence the phrase "get your ducks in a row"). Because the table of offsets contained coordinates to no better than a sixteenth of an inch, and also because there were sometimes errors in the table, the builder would nudge the spline a bit here and there to end up with a fair curve that went through the points as closely as possible. Only from a fair curve could you bend a plank to match the lines of the boat.

Tom

Cool.

"tdacon" wrote in news:m0ufg1$ahf$ snipped-for-privacy@dont-email.me:

The original definition of spline (according to the OED) was simply a long thin strip of wood - used to keep two boards aligned and flat (the cross-grain application Garrett describes is more modern - and depends on modern glues, I think).

A later definition is a spline was a rigid bar used to lock two pieces together - typically a wheel on an axle or something similar. Today we'd usually call that a key.

Because spline stock tended to be long and relatively thin, the name transferred to the lath used in lofting for shipbuilding, as David says. By extension the same name came to be used for small lead strips which would hold a curved shape - today we call these flexible curves (and they're usually plastic-covered).

Curves laid out with a spline (i.e. a flexible curve) were logically called "spline curves", and in the early days of computers mathematicians trying to analyse such curves by computers came up with math functions to represent the curve as a series of short segments; those functions in turn came to be called splines. By a further extension, the particular curve created by a spline function is also called a spline.

Probably more than anyone cares to know :-)

John

Word Origin and History for spline n.

"long, thin piece of wood or metal," 1756, from East Anglian dialect, perhaps from older Danish splind or North Frisian splinj.

I had always thought that lining up your ducks came from shooting them with a gun. Who knew?

snidely.too wrote, on Mon, 06 Oct 2014 12:22:31 -0700:

That explains why a woodworking spline, which is straight, would be applied to a draftsman's spline (which is decidedly curved).

Getting off subject, a little, but similar....

Long ago, I saw a carpenter use a metal Venetian blind slat to draw a strai ght line, 90 degrees to the front edge, across and up a counter top, with c ontinuous (curved corner) back splash. I thought that was a neat trick to get that accurate curved layout/alignment line. Since then, I'd gotten a Venetian blind slat for when I need to sketch a similar curved line.

Sonny

Maybe it does, or maybe it comes from ducklings following their mother, as Snidely said. It seems unlikely to come from the name of weights used with splines, though. According to Michael Quinion at World Wide Words, the oldest known example of "getting your ducks in a row" is from

But at Google Books I can't find any uses of "ducks" for spline weights before 1939. Instead they were called "weights" in print. No doubt drafters called them ducks earlier than 1939, but I can hardly imagine that the term was sufficiently widely known in 1889 to be used metaphorically in a newspaper.

(Of course, "I can hardly imagine" isn't proof.)

Okay, so one time? In band camp? tdacon was all, like:

Don't believe that for a second. Got a reliable source on that?

What part don't you believe, and upon what basis?

Tom