How to pretty print in ipython notebook via sympy?

Question

you need to use display:

from IPython.display import display

display(yourobject)

It will choose the appropriate representation (text/LaTex/png...), in recent enough version of IPython (6.0+) display is imported by default, still we recommend to explicitly import it.

The issue is with your init_printing statement. In a notebook, you do not want to run latex, instead you should use mathjax, so try this instead:

init_printing(use_latex='mathjax')

When I use this, I get normal pretty printing everywhere, even when I have a sympy expression as the last line of the cell.

This works,

from IPython.display import display, Latex
from sympy import *

x = symbols('x')
display(x)

int_x = Integral(cos(x)*exp(x), x)
result = "$${} = {}$$".format(latex(int_x), latex(int_x.doit()))
display(Latex(result))

derv_x = Derivative(cos(x)*exp(x), x)
result = "$${} = {}$$".format(latex(derv_x), latex(derv_x.doit()))
display(Latex(result))

try it for yourself.

I have asked a similar question (now linked to this one). After reading the answers and tinkering a bit, I conclude that there are 3 types of output one can get:

1. "Not pretty", pure text... "low quality". This is what one obtains with print(expression)

2. Pretty, pure text... "medium quality". This is what one obtains with

    import sympy as sym
    sympy.pprint(expression)
   

It still uses the same font and uses only characters to put together the mathematical expression. But it can, e.g., raise numbers for powers, pull fractions by laying out the horizontal line, etc.

3. Pretty, with graphics, symbols, etc... "high quality". This is what one obtains with

    import IPython.display as disp
    disp.display(expression)
   

This is the same as what one obtains as an output of the notebook cell, but now as a result of a command. Then, one can have multiple such outputs from a single notebook cell.

It is worth noting that:

1. sym.init_printing(... affects the output of sym.pprint.

2. sym.latex(expression) produces a LaTeX string for the expression. disp.Math(... produces the expression from LaTeX. These two may come in useful. Thus, disp.display(disp.Math(sym.latex(expression))) would produce the same output as disp.display(expression).