Weird LaTeX representation of sin^2 x

[nickkolok]

Describe the bug
LaTeX representation of sin^2 x depends on the way how the squared sinus was got.

To Reproduce

math.parse('(sin(x))^2').toTex()
"{\\left(\\sin\\left( x\\right)\\right)}^{2}"

math.parse('sin(x)*sin(x)').toTex()
"\\sin\\left( x\\right)\\cdot\\sin\\left( x\\right)"

math.simplify(math.parse('sin(x)*sin(x)')).toTex()
"{\\sin\\left( x\\right)}^{2}"

math.simplify(math.parse('(sin(x))^2')).toTex()
"{\\sin\\left( x\\right)}^{2}"

[josdejong]

The difference is that in your first expression you have extra parenthesis (sin(x))^2. These are redundant but will be part of the output. Function simplify will remove those parenthesis. You can also pass options to toTex to specify whether you want optional parenthesis or not:

math.parse('(sin(x))^2').toTex()
"{\\left(\\sin\\left( x\\right)\\right)}^{2}"

math.parse('(sin(x))^2').toTex({ parenthesis: 'auto' }) // default is 'keep'
"{\\sin\\left( x\\right)}^{2}"

Documentation: https://mathjs.org/docs/expressions/customization.html#custom-html-latex-and-string-output

[gwhitney]

But I think the original report needs some clarification: @nickkolok was your primary concern that the "usual" mathematical notation for the square of sin(x) would be rendered in TeX as \sin^2(x) rather than \sin(x)^2 ? Or are you ok with the latter notation, just concerned that the exact notation was depending on how you arrived at the "same" expression? (Note as Jos says, with respect to this second concern, mathjs is behaving as intended.)

[josdejong]

I'll close this issue now due to lack of response. Please reopen if needed.

[gwhitney]

I'd like to make a vote for leaving this open, because it is true that the usual way to write the square of sin x in mathematical notation is sin^2 x rather than the actually systematic (sin x)^2. If mathjs is striving to match mathematical practice (not sure if that's always the case) then it should detect this situation and convert to sin^2 x notation.

[josdejong]

Ok I'll reopen the issue.

So what we can improve here in toTex is basically remove parentheses of the left hand side of power and only then interpret it.