From 803416d08de0ee559aa3ab7a286c45c700cddf1e Mon Sep 17 00:00:00 2001
From: Ad5001 <mail@ad5001.eu>
Date: Tue, 10 Oct 2023 01:33:57 +0200
Subject: [PATCH] New system for integrals the same as for derivatives.

---
 .../ad5001/LogarithmPlotter/js/math/common.js | 63 ++++++++++++-------
 .../ad5001/LogarithmPlotter/js/math/latex.js  |  8 ++-
 2 files changed, 47 insertions(+), 24 deletions(-)

diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
index 9aabfd7..86d16e6 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
@@ -44,34 +44,55 @@ const parser = new ExprEval.Parser()
 
 parser.consts = Object.assign({}, parser.consts, evalVariables)
 
+/**
+ * Parses arguments for a function, returns the corresponding JS function if it exists.
+ * Throws either usage error otherwise.
+ * @param {array} args - Arguments of the function, either [ ExecutableObject ] or [ string, variable ].
+ * @param {string} usage1 - Usage for executable object.
+ * @param {string} usage2 - Usage for string function.
+ * @return {callable} JS function to call..
+ */
+function parseArgumentsForFunction(args, usage1, usage2) {
+    let f, target, variable
+    if(args.length == 1) {
+        // Parse object
+        f = args[0]
+        if(typeof f != 'object' || !f.execute)
+            throw EvalError(qsTranslate('usage', 'Usage: %1').arg(usage1))
+        let target = f
+        f = (x) => target.execute(x)
+    } else if(args.length == 2) {
+        // Parse variable
+        [f,variable] = args
+        if(typeof f != 'string' || typeof variable != 'number')
+            throw EvalError(qsTranslate('usage', 'Usage: %1').arg(usage2))
+        f = parser.parse(f).toJSFunction(variable, currentVars)
+    } else
+        throw EvalError(qsTranslate('usage', 'Usage: %1 or\n%2').arg(usage1).arg(usage2)))
+    return f
+}
+
 // Function definition
-parser.functions.integral = function(a, b, f, variable) {
+parser.functions.integral = function(a, b, ...args) {
+    let usage1 = qsTranslate('usage', 'integral(<from: number>, <to: number>, <f: ExecutableObject>)')
+    let usage2 = qsTranslate('usage', 'integral(<from: number>, <to: number>, <f: string>, <variable: string>)')
+    let f = parseArgumentsForFunction(args, usage1, usage2)
+    if(a == null || b == null)
+        throw EvalError(qsTranslate('usage', 'Usage: %1 or\n%2').arg(usage1).arg(usage2)))
+
     // https://en.wikipedia.org/wiki/Simpson%27s_rule
     // Simpler, faster than tokenizing the expression
-    f = parser.parse(f).toJSFunction(variable, currentVars)
     return (b-a)/6*(f(a)+4*f((a+b)/2)+f(b))
 }
 
 parser.functions.derivative = function(...args) {
-    let f, target, variable, x
-    if(args.length == 2) {
-        [f, x] = args
-        if(typeof f != 'object' || !f.execute)
-            throw EvalError(qsTranslate('usage', 'Usage: %1')
-                                .arg(qsTranslate('usage', 'derivative(<function: ExecutableObject>, <x: variable>)')))
-        target = f
-        f = (x) => target.execute(x)
-    } else if(args.length == 3) {
-        [f, variable, x] = args
-        if(typeof f != 'string')
-            throw EvalError(qsTranslate('usage', 'Usage: %1')
-                                .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)')))
-        f = parser.parse(f).toJSFunction(variable, currentVars)
-    } else
-        throw EvalError(qsTranslate('usage', 'Usage: %1 or\n%2')
-                            .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)')
-                            .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)'))))
-
+    let usage1 = qsTranslate('usage', 'derivative(<f: ExecutableObject>, <x: variable>)')
+    let usage2 = qsTranslate('usage', 'derivative(<f: string>, <variable: string>, <x: variable>)')
+    let x = args.pop()
+    let f = parseArgumentsForFunction(args, usage1, usage2)
+    if(x == null)
+        throw EvalError(qsTranslate('usage', 'Usage: %1 or\n%2').arg(usage1).arg(usage2)))
+        
     let derivative_precision = x/10
     return (f(x+derivative_precision/2)-f(x-derivative_precision/2))/derivative_precision
 }
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
index 4f25651..1e84912 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
@@ -71,16 +71,18 @@ function parif(elem, contents) {
  * @returns {string}
  */
 function functionToLatex(f, args) {
-    console.log("Generating latex", f, args)
     switch(f) {
         case "derivative":
             if(args.length == 3)
                 return '\\frac{d' + args[0].substr(1, args[0].length-2).replace(new RegExp(args[1].substr(1, args[1].length-2), 'g'), 'x') + '}{dx}';
             else
-                return '\\frac{d' + args[0] + '}{dx}';
+                return '\\frac{d' + args[0] + '}{dx}(x)';
             break;
         case "integral":
-            return '\\int\\limits_{' + args[0] + '}^{' + args[1] + '}' + args[2].substr(1, args[2].length-2) + ' d' + args[3].substr(1, args[3].length-2);
+            if(args.length == 4)
+                return '\\int\\limits_{' + args[0] + '}^{' + args[1] + '}' + args[2].substr(1, args[2].length-2) + ' d' + args[3].substr(1, args[3].length-2);
+            else
+                return '\\int\\limits_{' + args[0] + '}^{' + args[1] + '}' + args[2] + '(t) dt';
             break;
         case "sqrt":
             return '\\sqrt\\left(' + args.join(', ') + '\\right)';