The ce.assign() function not working properly

[Nits7029]

Heyy @arnog , you can visit here and check https://codesandbox.io/s/infallible-worker-kdshn7

UPDATE

• [x] ce.assign() takes a value without brackets..
• [x] How can I wrap a variable in \mathrm?
• [ ] The onInlineShortcut function does not work when attempting to type subscripts such as Q_{Ed}..
• [ ] How can I assign a value to a variable such as M_g,6.10a? I've added an example in sandbox

Description

I want to evaluate formulas with variables by using the compute-engine. But I tested one case It gives me wrong answer. you can view code to above sandbox link.

Steps to Reproduce

1. first I write formula and parse into compute engine like this

const ce = new ComputeEngine.ComputeEngine(); const f = ce?.parse(x+y+xyz);

3. Then i use ce.assign()to assign values to x, y and xyz like this.

ce?.assign('xyz', 22); ce?.assign('x', 10); ce?.assign('y', 20);

5. At last I use console.log to show diffrent results. but

Actual Behavior

it gives me results like this.

Simplyfy: xyz+x+y evaluate: 200z+30 final: 200z+30

Expected Behavior

And I would be expecting the result 52.

[arnog]

In LaTeX, xyz is x multiplied by y multiplied byt z. If you want to indicate a single, multi-letter, identifier, you need to wrap it, for example: const f = ce.parse("x+y+\\operatorname{xyz}");. If you make that change in the codepen, you will get the expected answer.

(BTW, new ComputeEngine() will never return null or undefined, so the optional chaining operator (?.) is superfluous)

[Nits7029]

@arnog Really appreciate your really fast response Yeah that's write and working for me. if I directly use output from math-field for above mentioned simple formula.

Please look at my code-sandbox: https://codesandbox.io/s/infallible-worker-kdshn7?file=/src/App.js

But in most cases, I need to use complex formulas. like updated on my sandbox. I want to use variables with subscripts. Could you please explain to me how it will possible?

in sandbox added required equation.

Steps to Reproduce

1. ce.parse('R_{A}\\cdot X_{\\mathrm{Ed}}-\\frac12\\cdot q\\cdot X_{\\mathrm{Ed}}^2-F\\left(X_{\\mathrm{Ed}}-A\\right)')
2. don't work ce.assign(). how would I assign value to a variable with subscript?

Actual Behavior

when i try to assign getting this error.

Expected Behavior

assign to value all the used variables in the formula and get an answer.

[arnog]

If you want the subscript to also be considered a single variable, you also need to wrap it, i.e. \mathrm{R_{A}}.

The corresponding identifier is R_A, so use that for assign, not the LaTeX representation.

[Nits7029]

@arnog Yeah that's working, But I have another confusion.

Based on your previous response, it appears that enclosing the variable with subscripts using \\mathrm is necessary. Is there a method to directly obtain the appropriately wrapped output from the math-field onInput event?

[arnog]

You can provide a onInlineShortcut handler that can automatically recognize multicharacter identifiers, based on the syntax you want to support. See https://cortexjs.io/mathlive/guides/shortcuts/#multicharacter-identifiers

[Nits7029]

Hey @arnog, thank you for your quick response. However, I am facing another problem. The onInlineShortcut function doesn't seem to recognize a subscript input when I try to use it. I have updated the example in the sandbox.

I added an input math-field where I'm attempting to input subscript variables, but onInlineShortcut fails to detect it. I also consulted the documentation, but I was unable to find a solution. Do you have any other ideas on how I could wrap my variables in \mathrm{} to assign a value and calculate? codesandbox link - here

[Nits7029]

@arnog How can I assign a value to a variable such as M_g,6.10a? I have included an example in the sandbox for reference.

In my example, I have the expression \\mathrm{M_{k,6.10a}}. When try I to ce.assign("M_g,6.10a", 10); I get an error.

Could you please assist me with this? How can I assign a value to variables in this manner?

[arnog]

Unfortunately, as the error message indicate, M_g,6.10a is not a valid identifier. The , (and .) characters are not allowed in identifiers. See https://cortexjs.io/math-json/#identifiers

[Nits7029]

@arnog Thanks for your response. Is there any way to get a list of used variables from LaTeX or a math field?

For instance, I have a LaTeX response in a math-field like this. \\mathrm{R_{A}}\\cdot \\mathrm{X_{Ed}}-\\frac12\\cdot q\\cdot \\mathrm{X_{Ed}}^2-F\\left(\\mathrm{X_{Ed}}-A\\right).

Is there any method or function that can provide me with an array or object of variables?

[arnog]

Depending on what you're looking for, either symbols or unknowns:

• ce.parse(...).unknowns
• ce.parse(...).symbols