# ToExpression not accepting standard TeX strings

I am having trouble entering equations in TeX form. I have actually tried a bunch of different equations and gotten similar errors. For example:

ToExpression["\\int_0^\\infty e^{-x^2} dx = \\frac{\\sqrt\\pi}2",TeXForm]


• You need to add a thin space before the dx: ToExpression["\\int_0^\\infty e^{-x^2}\\,dx = \\frac{\\sqrt\\pi}2",TeXForm]. – Simon Rochester Sep 25 '15 at 4:21
• @SimonRochester When I do that it returns a "ConditionalExpression", a completely wrong interpretation of the TeX string which should be an integral. – Tyler Durden Sep 25 '15 at 4:40
• Mathematica is doing the integral, with the e interpreted as an arbitrary variable. Change the e to E and Mathematica will verify your equation. – Simon Rochester Sep 25 '15 at 4:45

ToExpression["\\int_0^\\infty E^{-x^2}\\,dx = \\frac{\\sqrt\\pi}2", TeXForm, HoldForm]

which wraps the expression in HoldForm before evaluation. Note the thin space before dx, which is needed for Mathematica to properly interpret the integral syntax, and the capital E.
ToExpression["{HoldForm}[\\int_0^\\infty E^{-x^2}\\,dx = \\frac{\\sqrt\\pi}2]", TeXForm]