Follow PHP convention for scientific notation also for numbers formatted with sigfig

classes/local/evaluator.php

@@ -163,9 +163,9 @@ public function substitute_variables_in_text(string $text, bool $skiplists = tru
                 if ($skiplists && in_array($result->type, [token::LIST, token::SET])) {
                     continue;
                 }
-                // If the result is a number, we try to localize it, unless the admin settings do not
+                // If the result is a number or a numeric string, we try to localize it, unless the admin settings do not
                 // allow the decimal comma.
-                if ($result->type === token::NUMBER) {
+                if ($result->type === token::NUMBER || ($result->type === token::STRING && is_numeric($result->value))) {
                     $result = qtype_formulas::format_float($result->value);
                 }
 

classes/local/functions.php

@@ -636,6 +636,7 @@ public static function sigfig($number, $precision): string {
             get_string('error_func_second_posint', 'qtype_formulas', 'sigfig()'),
             self::POSITIVE | self::INTEGER
         );
+        $originalnumber = $number;
         $number = floatval($number);
         $precision = intval($precision);
 
@@ -657,7 +658,22 @@ public static function sigfig($number, $precision): string {
         // We only request decimals if $digitsafter is greater than zero.
         $digitsafter = max(0, $digitsafter);
 
-        return number_format($number, $digitsafter, '.', '');
+        // If the absolute value of the *original* number is >= 1e-4 and < 1e14, we can format
+        // it and return a string. The same is true if the rounded number is zero.
+        if ($number == 0 || (abs($originalnumber) >= 1e-4 && abs($originalnumber) < 1e14)) {
+            return number_format($number, $digitsafter, '.', '');
+        }
+
+        // If the absolute value of the original number was below 1e-4, but just reached that
+        // limit after rounding, it should be output as 0.0001, plus possibly some trailing zeroes.
+        if (abs($originalnumber) < 1e-4 && abs($number) == 1e-4) {
+            return sprintf("%.{$precision}H", $number);
+        }
+
+        // For all other cases, we force scientific notation. Note that we have to subtract 1
+        // from the requested precision, because with the E format, the parameter indicates
+        // the number of places *after* the decimal comma.
+        return sprintf('%.' . ($precision - 1) . 'E', $number);
     }
 
     /**

tests/evaluator_test.php

@@ -1348,6 +1348,33 @@ public function test_substitute_variables_in_text(): void {
         self::assertEquals($expected, $output);
     }
 
+    public function test_substitute_variables_in_text_with_sigfig(): void {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Define, parse and evaluate some variables.
+        $vars = 'a=0.3; b=sigfig(a, 2); c=0.000005; d=sigfig(c, 8); e=fact(19); f=sigfig(e, 3)';
+        $parser = new parser($vars);
+        $statements = $parser->get_statements();
+        $evaluator = new evaluator();
+        $evaluator->evaluate($statements);
+
+        // We only test the correct replacement of the numbers; correct interpretation of
+        // placeholders is covered in another test.
+        $text = '{a} -- {b} -- {c} -- {d} -- {e} -- {f}';
+        $output = $evaluator->substitute_variables_in_text($text);
+        $expected = '0.3 -- 0.30 -- 5.0E-6 -- 5.0000000E-6 -- 1.2164510040883E+17 -- 1.22E+17';
+        self::assertEquals($expected, $output);
+
+        // Setting the localised decimal separator, but disallow the decimal comma in the admin settings.
+        qtype_formulas_test_helper::define_local_decimal_separator();
+        set_config('allowdecimalcomma', 1, 'qtype_formulas');
+        self::assertEquals('1', get_config('qtype_formulas', 'allowdecimalcomma'));
+        $output = $evaluator->substitute_variables_in_text($text);
+        $expected = '0,3 -- 0,30 -- 5,0E-6 -- 5,0000000E-6 -- 1,2164510040883E+17 -- 1,22E+17';
+        self::assertEquals($expected, $output);
+    }
+
     public function test_substitute_variables_in_algebraic_formula(): void {
         // Define, parse and evaluate some variables.
         $vars = 'a=1; b=[2,3,4]; c={1,2,3}; x={1:10}; y={1:10}; k = [[1,2],[3,4]];';

tests/functions_test.php

@@ -627,6 +627,49 @@ public static function provide_sigfig_expressions(): array {
             ['-0.005', 'sigfig(-.005, 1)'],
             ['-0.0050', 'sigfig(-.005, 2)'],
             ['-0.00500', 'sigfig(-.005, 3)'],
+
+            ['9.99E-5', 'sigfig(0.0000999, 3)'],
+            ['9.990E-5', 'sigfig(0.0000999, 4)'],
+            ['1.00E-5', 'sigfig(0.0000100, 3)'],
+            ['1.000E-5', 'sigfig(0.0000100, 4)'],
+            ['-9.99E-5', 'sigfig(-0.0000999, 3)'],
+            ['-9.990E-5', 'sigfig(-0.0000999, 4)'],
+            ['-1.00E-5', 'sigfig(-0.0000100, 3)'],
+            ['-1.000E-5', 'sigfig(-0.0000100, 4)'],
+            ['1.23E-6', 'sigfig(0.000001234, 3)'],
+            ['1.2340E-6', 'sigfig(0.000001234, 5)'],
+            ['-1.23E-5', 'sigfig(-0.0000123, 3)'],
+            ['-1.230E-5', 'sigfig(-0.0000123, 4)'],
+
+            ['0.000100', 'sigfig(0.0001, 3)'],
+            ['0.0001000', 'sigfig(0.0001, 4)'],
+            ['0.0001', 'sigfig(0.00009995, 3)'],
+            ['9.995E-5', 'sigfig(0.00009995, 4)'],
+            ['-0.000100', 'sigfig(-0.0001, 3)'],
+            ['-0.0001000', 'sigfig(-0.0001, 4)'],
+            ['-0.0001', 'sigfig(-0.00009995, 3)'],
+            ['-9.995E-5', 'sigfig(-0.00009995, 4)'],
+
+            ['1.00E+14', 'sigfig(1e14, 3)'],
+            ['1.0000E+14', 'sigfig(1e14, 5)'],
+            ['1.23E+14', 'sigfig(1.23e14, 3)'],
+            ['1.2300E+14', 'sigfig(1.23e14, 5)'],
+            ['1.20E+14', 'sigfig(1.2e14, 3)'],
+            ['9.99E+14', 'sigfig(9.99e14, 3)'],
+            ['-1.230E+14', 'sigfig(-1.23e14, 4)'],
+
+            ['100000000000000', 'sigfig(99999999999999, 3)'],
+            ['100000000000000', 'sigfig(99999999999999, 5)'],
+            ['99900000000000', 'sigfig(99900000000000, 3)'],
+            ['-100000000000000', 'sigfig(-99999999999999, 3)'],
+            ['-100000000000000', 'sigfig(-99999999999999, 5)'],
+            ['-99900000000000', 'sigfig(-99900000000000, 3)'],
+
+            ['0.300', 'sigfig(0.3, 3)'],
+            ['123.00', 'sigfig(123, 5)'],
+            ['99999.0', 'sigfig(99999, 6)'],
+            ['-0.00123', 'sigfig(-0.00123, 3)'],
+            ['0.00', 'sigfig(0, 3)'],
         ];
     }
 

tests/renderer_test.php

@@ -336,6 +336,32 @@ public function test_substitution_of_local_variables(): void {
         $this->check_output_does_not_contain_stray_placeholders();
     }
 
+    public function test_right_answer_feedback_uses_appropriate_decimal_separator(): void {
+        // Setting the localised decimal separator, but disallow the decimal comma in the admin settings.
+        qtype_formulas_test_helper::define_local_decimal_separator();
+        self::assertEquals('0', get_config('qtype_formulas', 'allowdecimalcomma'));
+
+        $q = $this->get_test_formulas_question('testsinglenum');
+        $q->parts[0]->answer = '3.5';
+
+        $this->start_attempt_at_question($q, 'immediatefeedback', 1);
+        $this->process_submission(['0_0' => '42', '-submit' => 1]);
+        $this->check_output_contains_lang_string('correctansweris', 'qtype_formulas', '3.5');
+
+        // Now allowing the decimal comma to be used.
+        set_config('allowdecimalcomma', 1, 'qtype_formulas');
+        $this->start_attempt_at_question($q, 'immediatefeedback', 1);
+        $this->process_submission(['0_0' => '42', '-submit' => 1]);
+        $this->check_output_contains_lang_string('correctansweris', 'qtype_formulas', '3,5');
+
+        // Make sure the decimal comma is also applied for numbers that are string tokens.
+        $q = $this->get_test_formulas_question('testsinglenum');
+        $q->parts[0]->answer = 'sigfig(3.5, 3)';
+        $this->start_attempt_at_question($q, 'immediatefeedback', 1);
+        $this->process_submission(['0_0' => '42', '-submit' => 1]);
+        $this->check_output_contains_lang_string('correctansweris', 'qtype_formulas', '3,50');
+    }
+
     public function test_render_question_with_separate_unit_field(): void {
         $q = $this->get_test_formulas_question('testsinglenumunitsep');
         $q->parts[0]->unitpenalty = 0.5;