remove readthedocs references

quarto/precalc/functions.qmd

@@ -199,7 +199,7 @@ end
 The conditions for the `if` statements are expressions that evaluate to either `true` or `false`, such as generated by the Boolean operators `<`, `<=`, `==`, `!-`, `>=`, and `>`.
 
 
-If familiar with `if` conditions, they are natural to use. However, for simpler cases of "if-else" `Julia` provides the more convenient *ternary* operator: `cond ? if_true : if_false`. (The name comes from the fact that there are three arguments specified.) The ternary operator checks the condition and if true returns the first expression, whereas if the condition is false the second condition is returned. Both expressions are evaluated. (The [short-circuit](https://docs.julialang.org/en/v1/manual/control-flow/#Short-Circuit-Evaluation) operators can be used to avoid both evaluations.)
+If familiar with `if` conditions, they are natural to use. However, for simpler cases of "if-else" `Julia` provides the more convenient *ternary* operator: `cond ? if_true : if_false`. (The name comes from the fact that there are three arguments specified.) The ternary operator checks the condition and if true returns the first expression, whereas if the condition is false the second condition is returned. (Another useful control flow construct is [short-circuit](https://docs.julialang.org/en/v1/manual/control-flow/#Short-Circuit-Evaluation) evaluation.)
 
 
 For example, here is one way to define an absolute value function:
@@ -1129,6 +1129,11 @@ answ = 2
 radioq(choices, answ, keep_order=true)
 ```
 
+:::{.callout-note}
+## Note
+The parentheses in `(sin ∘ cos)(pi/4)` are needed due to the order of operations, with `cos(pi/4)` being evaluated first in the expression `sin ∘ cos(pi/4)`. Alternatively, one can define a function `sc = sin ∘ cos` (without parentheses), then call it through `sc(pi/4)`.
+:::
+
 ###### Question
 
 
@@ -1344,4 +1349,3 @@ The interval is a nearly exact estimate, as guaranteed by `IntervalArithmetic`.
 """]
 radioq(choices, 1)
 ```
-

quarto/precalc/julia_overview.qmd

@@ -321,7 +321,7 @@ log
 ### Built-in functions
 
 
-`Julia` has numerous built-in [mathematical](http://julia.readthedocs.io/) functions, we review a few here:
+`Julia` has numerous built-in [mathematical](https://docs.julialang.org/en/v1/manual/mathematical-operations/) functions, we review a few here:
 
 
 #### Powers logs and roots
@@ -631,5 +631,3 @@ plot(64 - (1/2)*32 * x^2, 0, 2)
   * SymPy has functions for manipulating expressions: `simplify`, `expand`, `together`, `factor`, `cancel`, `apart`,  $...$
   * SymPy has functions for basic math: `factor`, `roots`, `solve`, `solveset`, $\dots$
   * SymPy has functions for calculus: `limit`, `diff`, `integrate`, $\dots$
-
-

quarto/precalc/logical_expressions.qmd

@@ -269,7 +269,7 @@ A,B = true, false  ## also true, true; false, true; and false, false
 ## Precedence
 
 
-The question of when parentheses are needed and when they are not is answered by the [precedence](http://julia.readthedocs.org/en/latest/manual/mathematical-operations/#operator-precedence)  rules implemented. Earlier, we wrote
+The question of when parentheses are needed and when they are not is answered by the [precedence](https://docs.julialang.org/en/v1/manual/mathematical-operations/#Operator-Precedence-and-Associativity)  rules implemented. Earlier, we wrote
 
 
 ```{julia}
@@ -625,4 +625,3 @@ In the manual we can read that "In the expression `a && b`, the subexpression `b
 answ = 1
 radioq(choices, answ)
 ```
-

quarto/precalc/ranges.qmd

@@ -233,7 +233,7 @@ x = [0, 2, 4, 6, 8, 10]
 That is of course only part of the set of even numbers we want. Creating more might be tedious were we to type them all out, as above. In such cases, it is best to *generate* the values.
 
 
-For this simple case, a range can be used, but more generally a [comprehension](http://julia.readthedocs.org/en/latest/manual/arrays/#comprehensions) provides this ability using a construct that closely mirrors  a set definition, such as $\{2k: k=0, \dots, 50\}$. The simplest use of a comprehension takes this form (as we described in the section on vectors):
+For this simple case, a range can be used, but more generally a [comprehension](https://docs.julialang.org/en/v1/manual/arrays/#man-comprehensions) provides this ability using a construct that closely mirrors  a set definition, such as $\{2k: k=0, \dots, 50\}$. The simplest use of a comprehension takes this form (as we described in the section on vectors):
 
 
 `[expr for variable in collection]`
@@ -673,4 +673,3 @@ The [product](http://en.wikipedia.org/wiki/Arithmetic_progression) of the terms
 val = prod(1:2:19)
 numericq(val)
 ```
-

quarto/precalc/transformations.qmd

@@ -339,7 +339,7 @@ The von Bertanlaffy growth [equation](http://www.fao.org/docrep/W5449e/w5449e05.
 ##### Example: the pipeline operator
 
 
-In the last example, we described our sequence as scale, over, stretch, and up, but code this in reverse order, as the composition $f \circ g$ is done from right to left. A more convenient notation would be to have syntax that allows the composition of $g$ then $f$ to be written $x \rightarrow g \rightarrow f$. `Julia` provides the [pipeline](http://julia.readthedocs.org/en/latest/stdlib/base/#Base.|>) operator for chaining function calls together.
+In the last example, we described our sequence as scale, over, stretch, and up, but code this in reverse order, as the composition $f \circ g$ is done from right to left. A more convenient notation would be to have syntax that allows the composition of $g$ then $f$ to be written $x \rightarrow g \rightarrow f$. `Julia` provides the [pipeline](https://docs.julialang.org/en/v1/manual/functions/#Function-composition-and-piping) operator for chaining function calls together.
 
 
 For example, if $g(x) = \sqrt{x}$ and $f(x) =\sin(x)$ we could call $f(g(x))$ through:
@@ -645,4 +645,3 @@ q"S(D(f))(n) = f(n) - f(0)"
 answ = 1
 radioq(choices, answ, keep_order=true)
 ```
-

quarto/precalc/vectors.qmd

@@ -407,7 +407,7 @@ The last value of a vector is usually denoted by $v_n$. In `Julia`, the `length`
 
 :::{.callout-note}
 ## More on indexing
-There is [much more](http://julia.readthedocs.org/en/latest/manual/arrays/#indexing) to indexing than just indexing by a single integer value. For example, the following can be used for indexing:
+There is [much more](https://docs.julialang.org/en/v1/manual/arrays/#man-array-indexing) to indexing than just indexing by a single integer value. For example, the following can be used for indexing:
 
   * a scalar integer (as seen)
   * a range
@@ -990,4 +990,3 @@ q"zs^(1./2)"
 answ = 2
 radioq(choices, answ, keep_order=true)
 ```
-