Numerical Linear Algebra
Last edited: February 2, 2026FLOP
A FLOP is a “floating-point operations”. One addition, subtraction, multiplication, or division of two floating-point numbers.
Basic Linear Algebra Subroutines
BLAS Level 1
Vector-Vector operations
- inner product \(x^{T}y\) which is \(2n-1\) flops
- sum \(x+y\) and scale \(\alpha x\) which is \(n\) flops
BLAS Level 2
Matrix-vector product
\(y = Ax\) with \(A \in \mathbb{R}^{m \times n}\)
- standard multiply \(m\qty(2n - 1)\)
- \(2N\) if \(A\) is sparse with \(N\) non-zero elements
- \(2p\qty(n+m)\) if \(A\) is given as \(A = UV^{T}\), where \(U \in \mathbb{R}^{m \times p}\) and \(V \in \mathbb{R}^{n \times p}\), which is called a “banded” matrix (sparse everywhere except for a strip nexht to diagonal)
BLAS Level 3
Matrix-matrix operations
SU-EE364A FEb192026
Last edited: February 2, 2026Key Sequence
Notation
New Concepts
Important Results / Claims
Questions
Interesting Factoids
SU-EE364A FEB242026
Last edited: February 2, 2026Key Sequence
Notation
New Concepts
Important Results / Claims
Questions
Interesting Factoids
SU-SOC175 FEB232026
Last edited: February 2, 2026Implications: rapid population aging. 1-child policy means that cost of pensions, health care, and social services will thus rise.
- 1 in 6 now above 60
- 1 in 4 above 2030
- 1 in 3 by 2050
“get old before getting rich”
demography
1980-2010
- low dependency ratios
- high household savings rate
- large lavor supply
- “age of abundance”
decline
- rapidly aging population
- rapidly rising dependency ratios
- ageing population / rising health / retirement costs
- shrikning labor force, rising wages
- declining of deposits in bank system
- less capital
resulting dynamics
- labor force shrinking by 2 million workers per year
- manufacturing wages rising faster
- labor cost advantage almost gone
wages keep going up
Knee Socks
Last edited: February 2, 2026You got the lights on in the afternoon
And the nights are drawn out long
And you’re kissin’ to cut through the gloom
With a cough drop coloured tongue
And you were sittin’ in the corner with the coats all piled high
And I thought you might be mine
In a small world, on an exceptionally rainy Tuesday night
In the right place and time
When the zeros line up on the 24 hour clock
