Irrational skirt : Knitty.com

by Heather Farley

This is a pattern I first came up with over 10 years ago in high school, but abandoned quickly because I wasn't sure how to go about designing. I loved Pi and everything about math, so of course, I thought I should knit a skirt that incorporates the mathematical constant Pi, the prime numbers, and the Fibonacci sequence!

This skirt is knit as a long strip that is then seamed together into a spiral. The waist is high so that you can see all the digits of Pi even while wearing an untucked t-shirt. This skirt is designed to the size and length that you want: Pi is irrational and will continue for as long as you need! The skirt is black and white, reminiscent of old DOS computers. To add color, every prime-th digit is blue. The primes numbers are the numbers which can't be divided into smaller numbers and consist of 2, 3, 5, 7, 11, 13, 17, … That means that second, third, fifth, eleventh, thirteenth, seventeenth, etc., digits of Pi are blue (head nod to blue screen of death).

The width of the strip increases by one stitch whenever your row count is one of the Fibonacci numbers. The Fibonacci sequence is the sequence of numbers starting with 0 and 1 so that each number is the sum of the previous two numbers: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, etc. See how 8+13 = 21, 21 + 13 = 34, etc.

To make it easier, I've included a list of digits of Pi with the prime-th digits colored blue and a list of the first few Fibonacci numbers; it's unlikely you will need to go higher than that!

model: Heather Farley

photos: Adeline Lambert


SIZE XS[S, M, L, 1X, 2X, 3X] shown in size L with 2 inches of ease

FINISHED MEASUREMENTS
Circumference: 34[36, 40, 44, 48, 53, 55] inches
Length: 27[28, 28, 28, 28, 29, 30] inches

MATERIALS
Yarn
Knit Picks Swish DK [100% Superwash Wool; 123 yd per 50g skein];
[MC] Coal; 5[6, 7, 7, 8, 9, 10] skeins
[CC1] White; 1[1, 1, 1, 1, 2, 2] skeins
[CC2] Wonderland Heather; 1[1, 1, 1, 1, 1, 1] skein

Recommended needle size
[always use a needle size that gives you the gauge listed below -- every knitter's gauge is unique]
US #5/3.75mm needles for working flat
1 32-inch US #5/3.75mm circular needle
1 32-inch US #4/3.5mm circular needle
2 US #5/3.75 double pointed needles for i-cord
a spare US #6-8/4-5mm needle for bind off

Notions
stitch marker
yarn needle

GAUGE

22 sts/32 rows = 4 inches in stockinette stitch with US #5/3.75mm
24 sts/34 rows = 4 inches in pattern stitch US #4/3.5mm

PATTERN NOTES
[Knitty's list of standard abbreviations and techniques can be found here.]

Skirt is worked flat and then seamed in a spiral. Adding the waistband is done in the round. The final border on the bottom is worked in rows. The number "Pi" starts at your right hip and you can make the skirt as long as you'd like, finishing so that the "end" of Pi stops in front of your right leg.

Directions for Jeny's Surprisingly Stretchy Bind Off can be found here.

Charts
The charts for this pattern are very large and fit on a letter-sized page.
Click here and print the resulting page.

DIRECTIONS
Skirt
Cast on 2 stitches in MC onto needles for working flat.

Row 1 [RS]: k1, kfb. 1 st increased.

Row 2 [WS]: P.

Row 3 [RS]: K1, m1r, k to end. 1 st increased.

Repeat Rows 2-3 until 20 rows have been completed, ending with a WS row. 12 sts.

Next row [RS]: Work Pi Chart across.

From here, you will work the Pi Chart, placing the numbers in the last 11 sts of the RS rows/first 11 sts of the WS rows.

Once you've completed the Pi Chart, your numbers are set. From here, work the digits of Pi, following the Numbers Chart.

At the same time, work an M1R as shown in the chart 11 sts before the end of the row, on every Fibonnaci-numbered row -- that is, on Rows 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, and so forth.

When your strip of Pi (slice of Pi?) is 40[42, 46, 50, 54, 59, 61] inches long, steam block your wedge. Attach the tail of your strip under the 3.14… part so that the circumference of the resulting circle/waistband is 36[38, 42, 46, 50, 55, 57] inches.

*Knit 12 inches of the wedge.
Steam block wedge.
Mattress stitch it to the previous row.*

Repeat from * to * until the length of skirt is 22[23, 23, 23, 23, 24, 25] inches, or desired length.

The beginning of Pi (3.14...) will sit at the right hip bone. The end of the strip will hit at the middle of your right leg. When you have enough digits, add ellipses (...) at the end. The chart for the ellipses' point is on row 62 of the numbers chart.

Knit 6 rows.
Bind off with standard bind off. Steam block end. Finish mattress stitching end to strip above it.

Waistband
With RS facing, working with the smallest circular needle, in MC, pick up and knit a multiple of 5 stitches working around the top of the waistband.

Round 1: [K2, p1, p2tog] around.

Next round, establish ribbing: [K2, p2] around.

Work ribbing as set for 3 inches.

Eyelet round: [K2, yo, p2tog] around.

Continue in ribbing for 2 more inches.

Bind off, using Jeny's Surprisingly Stretchy Bind-off.

Scallop Edging
There will be a "corner" where your Pi strip ends and meets itself.

With RS facing, working with largest circular needles, rejoin MC at corner where the end meets the spiral above. Pick up and knit a multiple of 13 stitches along on the bottom edge. Work back and forth.

Row 1 [WS]: P.

Row 2 [RS]: Work Scallop Edging chart across.

Continue until chart is complete.

BO, using largest needle in your right hand to work the stitches, to ensure a loose and even edge.

Waist tie
Using 2 double pointed needles, and MC, CO 4 sts. Work i-cord for 36[39, 42, 46, 50, 54, 57] inches and thread it in and out of eyelet row to tie around waist.

FINISHING
Weave in ends. Block.

Wear with a slip and enjoy your Pi Day! (3/14/15).

ABOUT THE DESIGNER

Heather is a carfree knitter hailing from Oakland, CA. She hosts the Just Another Bay Area Knitting (JABAK) Podcast where she talks about her knitting and her biking adventures. She dabbles in programming and dreams about cake.

You can find her on Ravelry as TopHat.