Update labels on trig graphs

[siwelwerd]

In Section PF1 and maybe elsewhere, there are a bunch of trig graphs with tick marks labeled things like $\frac{1}{2} \pi$. But in looking at one of the images in Calculus CO-4 I figured out how to get these to typeset as $\frac{\pi}{2}$. We should copy that idea over to make the other graphs look nicer.

[siwelwerd]

Hmm, this is more involved than I thought it would be.

[siwelwerd]

Key insight from the Sage documentation: "Custom tick labels can be provided by providing the keyword tick_formatter with the list of labels, and simultaneously providing the keyword ticks with the positions of the labels."

Wired this up into a quick proof of concept

Old image:

New image:

Code:

f(x) = sin(x)
p=Graphics()
xmin=-2*pi
xmax=4*pi
delta=pi/4
custom_ticks=[]
custom_tick_labels=[]
for x in [xmin+delta*i for i in [0.. int((xmax-xmin)/delta)]]:
    if denominator(x) != 1:
        custom_tick_labels.append(f"$\\dfrac{{{latex(numerator(x))}}}{{{denominator(x)}}}$")
        custom_ticks.append(x)
    else:
        custom_ticks.append(x)
        custom_tick_labels.append(f"${latex(x)}$")
        
p+=plot(f, (x, xmin, xmax), color='blue', thickness=3, detect_poles=True,ticks=[custom_ticks,0.5], tick_formatter=[custom_tick_labels,"latex"])
show(p)

Probably the "right" thing to do is factor this into a function in our common.sage

[siwelwerd]

Probably the "right" thing to do is factor this into a function in our common.sage

Ah, but that's probably blocked by #361