Matrix Calculus for DeepLearning (Part2)
- We can’t compute partial derivatives of very complicated functions using just the basic matrix calculus rules we’ve seen Blog part 1.
- For example, we can’t take the derivative of nested expressions like sum(w + x) directly without reducing it to its scalar equivalent.
- The chain rule comes into play when we need the derivative of an expression composed of nested subexpressions.
- Chain rule helps in solving problem by breaking complicated expressions into subexpression whose derivatives are easy to compute.
- Chain rules are defined in terms of nested functions such as y=f(g(x)) for single variable chain rule.
- As we see in example we can handle nested expression of single variable x using this chain ruleonly when x can effect y through single data flow path.
- This chain rule that takes into consideration the total derivative degenerates to the single-variable chain rule when all intermediate variables are functions of a single variable.
This incredibly popular store is one of the hardest to socially distance in
- There are already early signs that many shoppers are eager to return to reopened TJ Maxx stores, despite lingering fears of the coronavirus.
- At the 1,100 stores open for at least a week in states that have reopened around the world, sales have risen above last year's levels, the company noted.
- Last week, TJX, which also owns the chain Marshalls, said it lost nearly $900 million last quarter.
- The company grew sales by attracting shoppers across income groups looking for bargains and found a niche among millennials, retail analysts say.
- But the coronavirus pandemic has bruised the US retail sector, choking off demand and forcing hundreds of thousands of stores to close temporarily.
- As companies try to clear out their excess inventory, they'll offload some merchandise to TJ Maxx and other discount chains.
JCPenney reopens 150 stores
- New York (CNN Business) - JCPenney, which filed for bankruptcy just two weeks ago, is in the process of reopening hundreds of stores.
- But the reopenings come at the same time it is planning to permanently close many stores to stem the losses that led to the bankruptcy filing.
- The day after the bankruptcy filing it announced plans to close 192 stores this year, although it has yet to identify which stores.
- The company plans to close another 50 stores next year.
- It started reopening a few dozen stores a week before the May 15 bankruptcy filing, and it opened more than 100 stores the week after the filing.
- Still JCPenney and department stores in general have had difficulties dealing with both customers' shift to buying more items online, and with online pickup offerings at big-box retailers such as Walmart and Target.
Let’s check in on Trump’s plan to bring drive-through testing to a drugstore near you
- Following Trump’s press conference in March, CVS, Walgreens, Walmart, and Target worked with the federal and state administrations to open drive-through testing sites across the country.
- The retail companies featured in the first press conference — CVS, Target, Walmart, and Walgreens — gradually opened testing sites over the ensuing weeks.
- By the time Trump announced the renewed effort on April 27, four of the companies had 57 testing sites among them, 50 of which opened a month after the March 13 announcement, according to the companies’ press releases.
- The second Trump press conference also featured supermarket chain Kroger, which has 30 test sites, though they appear to represent a partnership with states rather than the federal government.