Functions with identical auxiliary variables cannot be composed

When you define a function using a sum or integral, the calculator often gives the error “You can’t use ‘{variable}’ as an index because it’s already defined.” (for sums) or “You can’t use ‘{variable}’ as an integration variable because it’s already defined.” (for integrals) when you plug the function into a function which uses the same indexing/integration variable. Most notably this happens when you plug a function into itself. In essence, Desmos does not properly handle alpha conversion.

Here’s the link demonstrating several instances of this issue: Additionally, if you remove the backslash from the g(g(x)) line, the calculator becomes unresponsive until the page is refreshed in the sense that nothing will be computed if you change/add equations or move the window.

Thanks Daniel!

Thats something we might fix at some point, but in the meantime you’ll have to work around it by using different integration variables.