Show approximation sign for calculations involving an an derivation, integration or an equation

kalk/src/calculation_result.rs

@@ -6,14 +6,19 @@ use crate::kalk_value::{ComplexNumberType, KalkValue, ScientificNotation};
 pub struct CalculationResult {
     value: KalkValue,
     radix: u8,
+    is_approximation: bool,
 }
 
 // Wraps around KalkValue since enums don't work
 // with the javascript bindings.
 #[wasm_bindgen]
 impl CalculationResult {
-    pub(crate) fn new(value: KalkValue, radix: u8) -> Self {
-        CalculationResult { value, radix }
+    pub(crate) fn new(value: KalkValue, radix: u8, is_approximation: bool) -> Self {
+        CalculationResult {
+            value,
+            radix,
+            is_approximation,
+        }
     }
 
     #[allow(dead_code)]
@@ -33,7 +38,7 @@ impl CalculationResult {
 
     #[wasm_bindgen(js_name = toPrettyString)]
     pub fn to_string_pretty(&self) -> String {
-        if self.radix == 10 {
+        let value = if self.radix == 10 {
             self.value.to_string_pretty_radix(10)
         } else {
             format!(
@@ -41,6 +46,12 @@ impl CalculationResult {
                 self.value.to_string_pretty_radix(10),
                 self.value.to_string_pretty_radix(self.radix),
             )
+        };
+
+        if self.is_approximation {
+            format!("≈ {}", value)
+        } else {
+            value
         }
     }
 

kalk/src/interpreter.rs

@@ -19,6 +19,7 @@ pub struct Context<'a> {
     timeout: Option<u128>,
     #[cfg(not(target_arch = "wasm32"))]
     start_time: std::time::SystemTime,
+    is_approximation: bool,
 }
 
 impl<'a> Context<'a> {
@@ -38,6 +39,7 @@ impl<'a> Context<'a> {
             timeout,
             #[cfg(not(target_arch = "wasm32"))]
             start_time: std::time::SystemTime::now(),
+            is_approximation: false,
         }
     }
 
@@ -66,7 +68,7 @@ impl<'a> Context<'a> {
 
             if i == statements.len() - 1 {
                 if let Stmt::Expr(_) = stmt {
-                    return Ok(Some(CalculationResult::new(num, 10)));
+                    return Ok(Some(CalculationResult::new(num, 10, self.is_approximation)));
                 }
             }
         }
@@ -326,6 +328,10 @@ pub(crate) fn eval_fn_call_expr(
     expressions: &[Expr],
     unit: Option<&String>,
 ) -> Result<KalkValue, KalkError> {
+    if identifier.prime_count > 0 {
+        context.is_approximation = true;
+    }
+
     // Special functions
     match identifier.full_name.as_ref() {
         "sum" | "prod" => {
@@ -355,6 +361,8 @@ pub(crate) fn eval_fn_call_expr(
             }
         }
         "integrate" => {
+            context.is_approximation = true;
+
             return match expressions.len() {
                 3 => numerical::integrate_with_unknown_variable(
                     context,
@@ -778,6 +786,8 @@ fn eval_equation(
     right: &Expr,
     unknown_var: &Identifier,
 ) -> Result<KalkValue, KalkError> {
+    context.is_approximation = true;
+
     let expr = Expr::Binary(
         Box::new(left.clone()),
         TokenKind::Minus,

kalk/src/inverter.rs

@@ -353,7 +353,7 @@ fn invert_fn_call(
     let mut parameters_iter = parameters.iter();
     for argument in arguments {
         symbol_table.insert(Stmt::VarDecl(
-            Identifier::from_full_name(&parameters_iter.next().unwrap().to_string()),
+            Identifier::from_full_name(parameters_iter.next().unwrap()),
             Box::new(argument.clone()),
         ));
     }