Every time I think I know what's going on, suddenly there's another layer of complications.
2019年3月20日星期三
2019年3月18日星期一
Hermite and Smith forms
http://www.math.ubc.ca/~cass/siegel/Smith.pdf
https://en.wikipedia.org/wiki/Hermite_normal_form
SAS
https://en.wikipedia.org/wiki/Hermite_normal_form
SAS
HERMITE Function
The HERMITE function uses elementary row operations to compute the Hermite normal form of a matrix. For square matrices this normal form is upper triangular and idempotent.
If the argument is square and nonsingular, the result is the identity matrix. In general the result satisfies the following four conditions (Graybill, 1969):
- It is upper triangular.
- It has only values of 0 and 1 on the diagonal.
- If a row has a 0 on the diagonal, then every element in that row is 0.
- If a row has a 1 on the diagonal, then every off-diagonal element is 0 in the column in which the 1 appears.
The following statements compute an example from Graybill (1969):
a = {3 6 9, 1 2 5, 2 4 10}; h = hermite(a); print h;
http://support.sas.com/documentation/cdl/en/imlug/65547/HTML/default/viewer.htm#imlug_langref_sect260.htm
If the argument is a square matrix, then the Hermite normal form can be transformed into the row-echelon form by rearranging rows in which all values are 0.
The trace of the Hermite matirx is the rank.
2019年3月6日星期三
Row vector is a function
A row vector is a function takes a column vector as input and produce a scalar
2019年3月5日星期二
Lagrange Multipliers
We can connect Lagrange to Ridge and Lasso Regression.
http://www.math.harvard.edu/archive/21a_spring_09/PDF/11-08-Lagrange-Multipliers.pdf
http://www.math.harvard.edu/archive/21a_spring_09/PDF/11-08-Lagrange-Multipliers.pdf
2019年3月3日星期日
2019年2月23日星期六
Re-Dock the Explorer/Results Window in SAS
Solution:
For Explorer window: Use menu View >> Contents Only.
For Results window: Use menu View >> Results.
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