// Numbas version: exam_results_page_options
{"name": "Fourier Sketching (-3 to 3)  - Mod Function", "extensions": ["jsxgraph"], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"variable_groups": [], "name": "Fourier Sketching (-3 to 3)  - Mod Function", "tags": [], "statement": "<p style=\"text-align: center;\"></p>\n<p>By dragging the points A, B, and C, construct the graph of the function</p>\n<p>$ f(x) = \\mid \\simplify{ x - {a}}\\; \\mid $</p>\n<p>Note that in order to be marked correct, the points need to be within 0.2 of their correct values.</p>\n<p>Also note that you have to drag each of the points in order to be able to submit your answer.</p>", "preamble": {"js": "function dragpoint_board() {\n  var scope = question.scope;\n  \n  var a = scope.variables.a.value;\n  var b = scope.variables.b.value;\n  var c = scope.variables.c.value;\n\n  \n  var div = Numbas.extensions.jsxgraph.makeBoard('500px','500px',{boundingBox:[-3.3,5.5,3.3,-5.5],grid:true,withLabel:true});\n  $(question.display.html).find('#dragpoint').append(div);\n\n  var board = div.board;\n  \n// ceeate axis labels\n  \n   var label1 = board.create('point',[3.1,0.2],{name:'X',size:-1});\n   label1.setProperty({fixed:true});\n   var label2 = board.create('point',[0,14.3],{name:'y',size:-1});\n   label2.setProperty({fixed:true});\n  \n    \n    \n  //create draggable points\n\n\n    var line0 = board.create('line',[[-3,0],[-3,1]],{visible: false});\n    var np0 = board.create('glider',[-3,0,line0],\n      {\n        name:'A',\n        size:3\n      }\n    );\n\n    var line1 = board.create('line',[[-1,0],[0,0]],{visible: false});\n    var np1 = board.create('glider',[-0.5,0,line1],\n      {\n        name:'B',\n        size:3\n      }\n    );\n  \n    var line2 = board.create('line',[[3,0],[3,4]],{visible: false});\n    var np2 = board.create('glider',[3,0,line2],\n      {\n        name:'C',\n        size:3,\n      }\n    );\n \n  \n  \n  //shorthand to evaluate a mathematical expression to a number\n  function evaluate(expression) {\n    try {\n      var val = Numbas.jme.evaluate(expression,question.scope);\n      return Numbas.jme.unwrapValue(val);\n    }\n    catch(e) {\n      // if there's an error, return no number\n      return NaN;\n    }\n  }\n  \n  // set up points array\n  var num_points = 3;\n  var points = [np0, np1, np2];\n  \n  \n  // this function sets up the i^th point\n  function make_point(i) {\n    \n   var point = points[i];\n    \n    var x=point[0];\n    var y=point[1];\n    \n    // the contents of the input box for this point\n    var xstudentAnswer =  question.parts[0].gaps[i].display.studentAnswer;\n\n    \n    // when the student drags the point, update the gapfill input\n    point.on('drag',function(){\n      var x = Numbas.math.niceNumber(point.X());\n      var y = Numbas.math.niceNumber(point.Y());\n      \n      if(i===0)\n      {\n      var diff = y-b*(3+a);\n      xstudentAnswer(diff);\n      }\n      if (i===1)\n        {\n      var diff = x-b*(a);\n      xstudentAnswer(diff);\n      }\n      if (i===2)\n        {\n      var diff = y-b*(3-a);\n      xstudentAnswer(diff);\n      }\n    });\n    \n  }\n  \n  // create each point\n  for(var i=0;i<num_points;i++) {\n    make_point(i);\n  }\n     \n  \n  // create the parabola\n  var parabool = board.create('line',[np0,np1],{straightFirst:false, straightLast:false, strokeWidth:2,strokeColor:'blue'});\n  var parabool = board.create('line',[np1, np2],{straightFirst:false, straightLast:false, strokeWidth:2,strokeColor:'blue'});\n\n}\n\nquestion.signals.on('HTMLAttached',function() {\n  dragpoint_board();\n}); ", "css": "table#values th {\n  background: none;\n  text-align: center;\n}"}, "ungrouped_variables": ["a", "b", "c"], "functions": {"graph": {"parameters": [["a", "number"], ["b", "number"], ["c", "number"]], "definition": "// set up the board\nvar div = Numbas.extensions.jsxgraph.makeBoard('500px','500px',{boundingBox:[-3.3,5.5,3.3,-5.5],grid:true,withLabel:true,ticks:false});\n\nvar board = div.board;\n\nvar d = board.create('point',[3.1,0],{size:-1,name:'x'});\nd.setProperty({fixed:true});\nvar f = board.create('point',[0,14],{size:-1,name:'y'});\nf.setProperty({fixed:true});\nvar e = board.create('point',[-3,b*(3+a)],{size:3,name:'A'});\ne.setProperty({fixed:true});\nvar g = board.create('point',[a,0],{size:3,name:'B'});\ng.setProperty({fixed:true});\nvar e = board.create('point',[3,b*(3-a)],{size:3,name:'C'});\ne.setProperty({fixed:true});\n\n\nboard.create('functiongraph',[function(x){ return b*(-x + a);},-3,a],{strokeColor:'blue',strokeWidth:2});\nboard.create('functiongraph',[function(x){ return b*(x - a);},a,3],{strokeColor:'blue',strokeWidth:2});\n\nreturn div;", "language": "javascript", "type": "html"}}, "advice": "<p>The correct graph is shown below.</p>\n<p>{graph(a,b,c)}</p>", "parts": [{"showCorrectAnswer": true, "prompt": "<div id=\"dragpoint\"></div>", "showFeedbackIcon": true, "gaps": [{"showCorrectAnswer": true, "showFeedbackIcon": false, "mustBeReducedPC": 0, "variableReplacements": [], "scripts": {}, "mustBeReduced": false, "minValue": "-0.2", "type": "numberentry", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "maxValue": "0.2", "allowFractions": false, "variableReplacementStrategy": "originalfirst", "marks": "1", "correctAnswerStyle": "plain"}, {"showCorrectAnswer": true, "showFeedbackIcon": false, "mustBeReducedPC": 0, "variableReplacements": [], "scripts": {}, "mustBeReduced": false, "minValue": "-0.2", "type": "numberentry", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "maxValue": "0.2", "allowFractions": false, "variableReplacementStrategy": "originalfirst", "marks": "1", "correctAnswerStyle": "plain"}, {"showCorrectAnswer": true, "showFeedbackIcon": false, "mustBeReducedPC": 0, "variableReplacements": [], "scripts": {}, "mustBeReduced": false, "minValue": "- 0.2", "type": "numberentry", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "maxValue": "0.2", "allowFractions": false, "variableReplacementStrategy": "originalfirst", "marks": "1", "correctAnswerStyle": "plain"}], "variableReplacements": [], "scripts": {}, "marks": 0, "variableReplacementStrategy": "originalfirst", "type": "gapfill"}], "variablesTest": {"maxRuns": "200", "condition": ""}, "metadata": {"description": "", "licence": "Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International"}, "rulesets": {}, "extensions": ["jsxgraph"], "variables": {"b": {"group": "Ungrouped variables", "description": "", "name": "b", "templateType": "anything", "definition": "random(1)"}, "a": {"group": "Ungrouped variables", "description": "", "name": "a", "templateType": "anything", "definition": "random(-2..2)"}, "c": {"group": "Ungrouped variables", "description": "", "name": "c", "templateType": "anything", "definition": "random(1)"}}, "type": "question", "contributors": [{"name": "Gareth Woods", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/978/"}]}]}], "contributors": [{"name": "Gareth Woods", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/978/"}]}