REPORTER 22.1

Example 2: Magnitude from the Three Vector Components

Example 2: Magnitude from the three vector components

Problem

Given three variables X, Y and Z calculate the vector magnitude and store it in a variable LENGTH.

Solution

Copy Code
JavaScript
// Get variable values from template
var x = Template.GetCurrent().GetVariableValue("X");
var y = Template.GetCurrent().GetVariableValue("Y");
var z = Template.GetCurrent().GetVariableValue("Z");
  
// Check that the variables exist
if (x == null) throw Error("no X variable");
if (y == null) throw Error("no Y variable");
if (z == null) throw Error("no Z variable");
  
// Extract numbers from variables
var X = parseFloat(x);
var Y = parseFloat(y);
var Z = parseFloat(z);
  
// Check that the variables are valid numbers
if (isNaN(X)) throw Error("X " + x + " is not a valid number");
if (isNaN(Y)) throw Error("Y " + y + " is not a valid number");
if (isNaN(Z)) throw Error("Z " + z + " is not a valid number");
  
// Calculate magnitude
var length = Math.sqrt(X*X + Y*Y + Z*Z);
  
// Check for valid magnitude
if (isNaN(length)) throw Error("Bad vector magnitude");
  
// Create new variable LENGTH
var lvar = new Variable(Template.GetCurrent(), "LENGTH",
                        "vector magnitude", length);



 
  Discussion
 




 This is done using very similar methods to example 1. The only differences 
  here are using the function
 
  Math.sqrt()
 
 and we 
  do not use the standard
 
  Number.toFixed()
 
 function 
  as the length could be smaller than 2 decimal places. Instead we could use
 
  Number.toPrecision()
 
 or
 
  Number.toExponential()
 
 if we wanted to format 
  the result instead of leaving it with several decimal places.




 The source code for this example is available
 
  here
 
 .






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