matmul operator doesn't work on Python 3.4 and less.

[marcrleonard]

from p5 import *

def setup():
    size(640, 360)
    no_stroke()
    background(204)

def draw():
    if mouse_is_pressed:
        fill(random_uniform(255), random_uniform(127), random_uniform(51), 127)
    else:
        fill(255, 15)

    circle_size = random_uniform(low=10, high=80)

    circle((mouse_x, mouse_y), circle_size)

def key_pressed(event):
    background(204)

run()

I'm running p5 in a pipenv environment, python 3.4
Every sketch I run yields an error in OSX:

Traceback (most recent call last):
  File "/Users/marcleonard/Projects/p5/sketch.py", line 1, in <module>
    from p5 import *
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/__init__.py", line 19, in <module>
    from .sketch import *
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/sketch/__init__.py", line 19, in <module>
    from .base import *
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/sketch/base.py", line 29, in <module>
    from ..opengl import renderer
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/opengl/__init__.py", line 19, in <module>
    from .renderer import *
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/opengl/renderer.py", line 33, in <module>
    from ..pmath import matrix
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/pmath/__init__.py", line 20, in <module>
    from .vector import *
  File "/Users/marcleonard/.local/share/virtualenvs/p5-vgNG_uZz/lib/python3.4/site-packages/p5/pmath/vector.py", line 321
    return np.arccos( (self @ other) / (self.magnitude * other.magnitude))
                            ^
SyntaxError: invalid syntax

[marcrleonard]

using the @ symbol for matrix multiplication was added in python3.5
https://www.python.org/dev/peps/pep-0465/

python3.5 should be listed as a requirement.

[abhikpal]

Ahh.. yes! Thanks for pointing that out! I think we can just change the code to not use @ for matrix multiplication. Someone just needs to read through the code and replace all @ with np.dot or equivalent.

[arihantparsoya]

Even after replacing all @ with np.dot there are problems with python3.4 version:

    from p5 import *
  File "/Users/arihantparsoya/Documents/p5/p5/__init__.py", line 19, in <module>
    from .sketch import *
  File "/Users/arihantparsoya/Documents/p5/p5/sketch/__init__.py", line 19, in <module>
    from .base import *
  File "/Users/arihantparsoya/Documents/p5/p5/sketch/base.py", line 29, in <module>
    from ..opengl import renderer
  File "/Users/arihantparsoya/Documents/p5/p5/opengl/__init__.py", line 19, in <module>
    from .renderer import *
  File "/Users/arihantparsoya/Documents/p5/p5/opengl/renderer.py", line 33, in <module>
    from ..pmath import matrix
  File "/Users/arihantparsoya/Documents/p5/p5/pmath/__init__.py", line 22, in <module>
    from .curves import *
  File "/Users/arihantparsoya/Documents/p5/p5/pmath/curves.py", line 46
    ret_value = func(*new_args, parameter, **kwargs)
                                       ^
SyntaxError: only named arguments may follow *expression

[abhikpal]

Hmm.. interesting. I think the new culprit is the tuple unpacking:

    ret_value = func(*new_args, parameter, **kwargs)

We'll have to look through the code to see if this is really needed. If yes, then we add Python 3.5 as a dependency, else re-write it to be compatible for versions less than 3.5.