QBobWatson / gt-linalg

Interactive Linear Algebra, free online textbook at Georgia Tech
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Feedback on spans #414

Open ToolChainGang opened 2 years ago

ToolChainGang commented 2 years ago

In reference to version 224734d7be7ff0c4a8adb3a206356ea122112f33

(Section 2.2)

A Picture of a Consistent System [...]: This entire paragraph is awkwardly worded with confusing directional references. Consider a complete rewrite to more clearly identify the flow of the text with less dependence on "above", "below" and "following". "Below" and "following" are confusing at the outset.

"Solve this equation": missing "click and drag" text, but the grid doesn't have click/draggable elements so this may be on purpose. Or, the grid should have click/draggable elements and text is missing.

Consider examining each example coord box to see if it omits a needed "click and drag" text. Will not report further instances of this.

"A picture of the above equation": Open controls overlays the final vector, making it impossible to see what you're doing (Firefox and Chrome), and since the grid has no click/drag features, this makes the example difficult to solve.

"It will be important to know what are all linear combinations of a set of vectors v 1 , v 2 ,..., v k in R n . ": Consider putting "are" at the end, as in: "It will be important to know what all linear combinations of a set of vectors v 1 , v 2 ,..., v k in R n are. "

"The vertical line is “such that”; everything to the left of it is": semicolon should be comma (or colon).

"All mathematical notation is only shorthand: any sequence of symbols must translate into a usual sentence.": Consider removing adverb "only" and restriction "must", and replace "usual" with "simple". "Mathematical notation is just shorthand for a mathematical sentence."

"Three characterizations": Putting the math in the middle of the sentence breaks up the flow. Consider putting all text before the math in all 3 cases: "This vector equation has a solution: ...", and "This linear equation ... is consistent:".

"the origin and the heads of the vectors. Note that three...": Note that in this sentence "origin" is used, which is more clear than "tail". Reference previous error about using "head" and "tail": "origin" is a good substitute for "start" as written in that feedback note.

The examples are really well done. Moving the span from R(n) to R(n-1) makes the display "pop" into the lower dimension by changing color. This "snap to" feature makes the display easy to see and play with.