# Hello world!

This is my professional blog where I will be writing about data science, programming, math and, in general, about technical sciences. Lets test things out. I wonder how Jekyll or rather how the specified highlighter renders code. By default Jekyll 3.0+ uses Rouge.

# Ruby

(example from Jekyll documentation)

```
def show
@widget = Widget(params[:id])
respond_to do |format|
format.html # show.html.erb
format.json { render json: @widget }
end
end
```

# R

```
# Read in a default data set
data(cars)
head(cars)
```

```
speed dist
1 4 2
2 4 10
3 7 4
4 7 22
5 8 16
6 9 10
```

```
summary(cars)
```

```
speed dist
Min. : 4.0 Min. : 2.00
1st Qu.:12.0 1st Qu.: 26.00
Median :15.0 Median : 36.00
Mean :15.4 Mean : 42.98
3rd Qu.:19.0 3rd Qu.: 56.00
Max. :25.0 Max. :120.00
```

```
# Do a simple regression model with distance as a dependent variable. Include intercept because of non zero mean.
model<-lm(dist ~ speed,cars)
summary(model)
```

```
Call:
lm(formula = dist ~ speed, data = cars)
Residuals:
Min 1Q Median 3Q Max
-29.069 -9.525 -2.272 9.215 43.201
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -17.5791 6.7584 -2.601 0.0123 *
speed 3.9324 0.4155 9.464 1.49e-12 ***
---
Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
Residual standard error: 15.38 on 48 degrees of freedom
Multiple R-squared: 0.6511, Adjusted R-squared: 0.6438
F-statistic: 89.57 on 1 and 48 DF, p-value: 1.49e-12
```

According to the regression model, the stopping distance strongly depends on the speed of the car (duh!).

# Python

```
# A simple primality test that I remember off the top of my head
def isprime(n):
ans = 'is prime'
if n == 1:
ans = 'not prime'
elif n == 2 or n == 3:
return ans
else:
for i in range(2,int(n ** 0.5)+1):
if n % i is 0:
ans = 'not prime'
return ans
```

The highlighter works as intended. To make sure I remember the primality test correctly let’s run this code. I am using trinket.io to embed a python interpreter in my website. A very neat thing. You can see it below:

After running the code it seems like my primality test works correctly.

Jekyll also allows to include gists. I will embed the code that produces the news list on my main page. Let’s see what the gist looks like: Looks neat.

# Latex

Next, let me try to use $\LaTeX$:

- Here is an inline latex of the Euler identity: $e^{i\pi} + 1 = 0$
- Display latex of one of my favourite primality tests, the AKS test:

\[(x-a)^n \equiv (x^n-a)\]An integer $n$ is prime iff the congruence relation

holds for all inetegers $a$ that are coprime to $n$.

Thats pretty much it for the testing. I am working on a bunch of posts and one of them will be a step by step guide of how I built this website. Hopefully, it will be helpful to people who intend to use jekyll for their blogging needs. Until later.