julia-tutorial.sagews

This is a tutorial worksheet for SageMathCloud's Julia interface. This is orthogonal to IJulia and is a completetely different approach.

See http://julia.readthedocs.org/en/latest/manual/getting-started/

WARNING: Currently if you put %julia at the start of a cell it will be properly Julia syntax highlighted. If you just switch to Julia mode (with default_mode), then Python syntax highlighting happens instead. This is a temporary "not implemented" issue and won't be hard to fix.

%auto
%default_mode julia

1 + 2

3

ans

3

%md(hide=False)
Note that % modes *do* work here (we have markdown right here),
unlike in IJulia, and you can escape to different other systems, convert variables back and forth, etc.

Note that % modes do work here (we have markdown right here), unlike in IJulia, and you can escape to different other systems, convert variables back and forth, etc.

%python
i = sum(range(50))
julia.eval("i=%s"%i)

'1225'

# this is in julia
i

1225

i = i + 10

1235

%python
julia('i')._sage_()

1235

︠83201484-da77-4daf-b718-4e2467319bfai︠
%md

Sage pexepct modes have some interesting depth, for example:

Sage pexepct modes have some interesting depth, for example:

%sage
a = julia('12')
b = julia('45')
a+b

57

%sage
(a+b).sin()  # call julia's sin

0.43616475524782494

︠d4cdb014-20ff-42f6-87f1-f1aa44035da2i︠
%md
## Back to the tutorial...

Back to the tutorial...

println("Greetings! 你好! 안녕하세요?")

Greetings! 你好! 안녕하세요?

# Assign the value 10 to the variable x
x = 10

10

# Doing math with x's value
x + 1

11

# Reassign x's value
x = 1 + 1

2

# You can assign values of other types, like strings of text
x = "Hello World!"

"Hello World!"

x = 1.0

1.0

y = -3

-3

Z = "My string"

"My string"

customary_phrase = "Hello world!"

"Hello world!"

UniversalDeclarationOfHumanRightsStart = "人人生而自由，在尊严和权力上一律平等。"

"人人生而自由，在尊严和权力上一律平等。"

# Unicode names (in UTF-8 encoding) are allowed:
δ = 0.00001
안녕하세요 = "Hello"

"Hello"

%julia
δ + x

1.00001

pi

π = 3.1415926535897...

pi = 3

Warning: imported binding for pi overwritten in module Main 3

sqrt(100)

10.0

sqrt = 4

Warning: imported binding for sqrt overwritten in module Main 4

x = 3
2x^2 - 3x + 1

10

3(2 - 5im)^-1.0

0.20689655172413796 + 0.5172413793103449im

greet = "Hello"
whom = "world"
string(greet, ", ", whom, ".\n")

"Hello, world.\n"

"$greet, $whom.\n"

"Hello, world.\n"

function f(x,y)
  x + y
end

f (generic function with 1 method)

f(2,3)

5

∑(x,y) = x + y

∑ (generic function with 1 method)

∑(2,3)

5

%sage
# we overwrote sqrt above, and I don't know how to undo that, so
# just force a restart of the backend julia process
julia.quit()

# or we could use "workspace()"
︠88f52cd0-b4a2-40bd-984d-212fa34e02c0︠
i = 5

5

workspace()

# this *should* result in an error:
i

Error in lines 1-1 Traceback (most recent call last): File "/projects/4a5f0542-5873-4eed-a85c-a18c706e8bcd/.sagemathcloud/sage_server.py", line 862, in execute exec compile(block+'\n', '', 'single') in namespace, locals File "", line 1, in <module> File "/projects/4a5f0542-5873-4eed-a85c-a18c706e8bcd/.sagemathcloud/sage_server.py", line 897, in execute_with_code_decorators print code_decorator.eval(code, locals=self.namespace), File "/projects/4a5f0542-5873-4eed-a85c-a18c706e8bcd/.sagemathcloud/julia.py", line 114, in eval raise RuntimeError(julia_error) RuntimeError: ERROR: i not defined

%julia
# use %julia for better syntax highlighting/code folding, etc. for now.
function hypot(x,y)
  x = abs(x)
  y = abs(y)
  if x > y
    r = y/x
    return x*sqrt(1+r*r)
  end
  if y == 0
    return zero(x)
  end
  r = x/y
  return y*sqrt(1+r*r)
end

hypot (generic function with 1 method)

hypot(3, 4)

5.0