Java编写的用最小二乘拟合曲线（带图形）

import java.io.*; import java.util.*; /** Class for simple console input. A class designed primarily for simple keyboard input of the form one input value per line. If the user enters an improper input, i.e., an input of the wrong type or a blank line, then the user is prompted to reenter the input and given a brief explanation of what is required. Also includes some additional methods to input single numbers, words, and characters, without going to the next line. */ public class SavitchIn { /** Reads a line of text and returns that line as a String value. The end of a line must be indicated either by a new-line character '\n' or by a carriage return '\r' followed by a new-line character '\n'. (Almost all systems do this automatically. So you need not worry about this detail.) Neither the '\n', nor the '\r' if present, are part of the string returned. This will read the rest of a line if the line is already partially read. */ public static String readLine( ) { char nextChar; String result = ""; boolean done = false; while (!done) { nextChar = readChar( ); if (nextChar == '\n') done = true; else if (nextChar == '\r') { //Do nothing. //Next loop iteration will detect '\n'. } else result = result + nextChar; } return result; } /** Reads the first string of nonwhitespace characters on a line and returns that string. The rest of the line is discarded. If the line contains only whitespace, the user is asked to reenter the line. */ public static String readLineWord( ) { String inputString = null, result = null; boolean done = false; while(!done) { inputString = readLine( ); StringTokenizer wordSource = new StringTokenizer(inputString); if (wordSource.hasMoreTokens( )) { result = wordSource.nextToken( ); done = true; } else { System.out.println( "Your input is not correct. Your input must"); System.out.println( "contain at least one nonwhitespace character."); System.out.println( "Please try again. Enter input:"); } } return result; } /** Precondition: The user has entered a number of type int on a line by itself, except that there may be whitespace before and/or after the number. Action: Reads and returns the number as a value of type int. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines. */ public static int readLineInt( ) { String inputString = null; int number = -9999;//To keep the compiler happy. //Designed to look like a garbage value. boolean done = false; while (! done) { try { inputString = readLine( ); inputString = inputString.trim( ); number = Integer.parseInt(inputString); done = true; } catch (NumberFormatException e) { System.out.println( "Your input number is not correct."); System.out.println( "Your input number must be"); System.out.println( "a whole number written as an"); System.out.println( "ordinary numeral, such as 42"); System.out.println("Minus signs are OK," + "but do not use a plus sign."); System.out.println("Please try again."); System.out.println("Enter a whole number:"); } } return number; } /** Precondition: The user has entered a number of type long on a line by itself, except that there may be whitespace before and/or after the number. Action: Reads and returns the number as a value of type long. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines. */ public static long readLineLong( ) { String inputString = null; long number = -9999;//To keep the compiler happy. //Designed to look like a garbage value. boolean done = false; while (! done) { try { inputString = readLine( ); inputString = inputString.trim( ); number = Long.parseLong(inputString); done = true; } catch (NumberFormatException e) { System.out.println( "Your input number is not correct."); System.out.println( "Your input number must be"); System.out.println( "a whole number written as an"); System.out.println( "ordinary numeral, such as 42"); System.out.println("Minus signs are OK," + "but do not use a plus sign."); System.out.println("Please try again."); System.out.println("Enter a whole number:"); } } return number; } /** Precondition: The user has entered a number of type double on a line by itself, except that there may be whitespace before and/or after the number. Action: Reads and returns the number as a value of type double. The rest of the line is discarded. If the input is not entered correctly, then in most cases, the user will be asked to reenter the input. In particular, this applies to incorrect number formats and blank lines. */ public static double readLineDouble( ) { String inputString = null; double number = -9999;//To keep the compiler happy. //Designed to look like a garbage value. boolean done = false; while (! done) { try { inputString = readLine( ); inputString = inputString.trim( ); number = Double.parseDouble(inputString); done = true; } catch (NumberFormatException e) { System.out.println( "Your input number is not correct."); System.out.println( "Your input number must be"); System.out.println( "an ordinary number either with"); System.out.println( "or without a decimal point,"); System.out.println("such as 42 or 9.99"); System.out.println("Please try again."); System.out.println("Enter the number:"); } } return number; } /** Precondition: The user has entered a number of type float on a line by itself, except that there may be whitespace