issue145.do.txt

===== Exercise: my first exercise =====
Here goes a general introduction to the exercise.


|-----------------------------------------------------|
| Begin-end directive | Behavior                      |
|-----l--------------------l--------------------------|
| |bsubex - |esubex   | Subexercise                   |
| |bans - |eans       | Answer                        |
| |bsol - |esol       | Solution                      |
| |bhint - |ehint     | Hint                          |
|-----------------------------------------------------|


aaaa


|-----------------------------------------------------|
| Commands            | Behavior                      |
|--l----------------------------l---------------------|
| === Exercise/Example/..: .. === | Header with Exercise, Problem, Project, or Example title |
| file=               | Answer file                   |
| files=              | Answer files, comma separated |
| solution=           | Solution file                 |
|-----------------------------------------------------|


aaaa

|-------------------------------------------------------------|
| Command option      | Behavior                              |
|--l-------------------------------------l--------------------|
| --without_answers   | Turn off output of answers            |
| --without_solutions | Turn off output of solutions          |
| --answers_at_end    | Answers in the end of the document    |
| --solutions_at_end  | Solutions in the end of the document  |
|-------------------------------------------------------------|

aaaa

|-------------------------------------------------------------|
| Command             | Behavior                              |
|-----------l-------------------------l-----------------------|
| !anshide            | Hide answers until !solhide           |
| !solhide            | Hide solutions until !solhide         |
| !ansoff             | Restore answers' visibility           |
| !soloff             | Restore solutions visibility          |
| !ansdocend          | Answers in the end of the document    |
| !soldocend          | Answers in the end of the document    |
|-------------------------------------------------------------|

=== Solutions ===
idx{`--without_answers`}
idx{`--without_solutions`}
idx{`--answers_at_end`}
idx{`--solution_at_end`}

The solution environment that can be created with `!bsol` and `!esol` allows inline



!bsubex
Predict what this code will do

!bc pycod-t
a = 2
!ec

!bans
Prints `2`
!eans
!esubex

!bsubex
Modify the program so that it prints 2, 3 and 4.

!bans
There are many ways to do this. We will show two of them.
!eans

!bsol
!bc pycod
b = 5
!ec
An alternative:
!bc pycod
b = 4
!ec
!esol
!esubex


===== bug =====
__More on $\theta$.__ Here is more text following headline with math.

Newcommands must also be tested in this \report:
$\half$, $\halfi$, $\x$, $\Ddt{u}$,
both inline and in block:

!bt
\begin{align}
\Ddt{u} &= 0\nonumber
\\
\half &= \halfi\\
\half\x &= \normalvec
\end{align}
!et

===== Exercise: my second exercise =====

Here goes a general introduction to the exercise.

!bsubex
Implement this difference equation in Python
and generate a plot for values of $x$ from 1 to 10.

!bt
\begin{equation}
x_{n+1} = 1.5 x_n -20
x_0 = 20
\end{equation}
!et

!bsol
!bc pycod
from matplotlib import pyplot as plt
x = [20]
i = 1
while i < 10:
    x.append(1.5 * x[i-1] - 20)
    i = i + 1

plt.plot(x)
plt.show()
!ec

!esol
!esubex

!bsubex
Question without code answer:
Can you think of an example case that has this difference equation as model?

!bans
Not really.
!eans
!esubex

!bsubex
Another question without code answer.
!bans
Nothing to answer...
!eans
!esubex