How to handle order of operations when making a trigonometric calculator

Update: Unfortunately i was unable to finish this assignment, although the deadline has passed i feel that i have invested too much time on this to just set it aside and i know that I am close to the solution. This is the code that i have produced over the past couple of days ``` /* "[5*sin(3*t+0.523),4*cos(2*t)]" */ import java.util.*; // import javax.swing.*; // import javax.swing.JFrame; // lets me create the window import java.awt.Graphics; // for drawing import java.awt.Point; // allows the use of points import java.awt.Graphics2D; // for drawing import javax.swing.JComponent; // for drawing import javax.swing.JPanel; // for drawing import java.lang.Math; // for trig import java.util.Iterator; import java.util.LinkedList; import java.util.Queue; public class Graph { //-------------------Queue---String----------------------------------------------------------------// public static double[] queue_str(String str, double[] results) { Queue<Character> token = new LinkedList<Character>(); Queue<Double> numbers = new LinkedList<Double>(); double[] t_vals = new double [5]; int t_vals_len = t_vals.length; int numbers_sz = 0; int token_sz = 0; t_vals[0] = 7.0; t_vals[1] = 2.0; t_vals[2] = 3.0; t_vals[3] = 4.0; t_vals[4] = 3.0; char temp_token; char temp_char; double p1_num = 0, temp_num = 0, p2_num = 0; if(results.length == 0){} for(int i = 0; i < str.length(); i++) { if(str.charAt(i) == '*' && str.charAt(i) != 't' || str.charAt(i) == '+'&& str.charAt(i) != 't' || str.charAt(i) == '-' && str.charAt(i) != 't' || str.charAt(i) == '/' && str.charAt(i) != 't') { temp_token = str.charAt(i); token.add(temp_token); token_sz ++; String[] parts = str.split("\\" + String.valueOf(temp_token)); String str1 = parts[0]; String str2 = parts[1]; if(str1.matches("-?\\d+(\\.\\d+)?")) { p1_num = Double.parseDouble(str1); numbers.add(p1_num); numbers_sz ++; } if(str2.matches("-?\\d+(\\.\\d+)?")) { p2_num = Double.parseDouble(str2); numbers.add(p2_num); numbers_sz ++; } } else if(str.charAt(i) == 't') { temp_token = str.charAt(i); String [] t_char = str.split(String.valueOf(temp_token)); for(int k = 0; k < t_vals_len; k++) { temp_num = t_vals[k]; numbers.add(temp_num); numbers_sz ++; } } } double[] dbl_numbs = new double [numbers_sz]; while(numbers.peek()!=null) { for (int iter = 0; iter < numbers_sz; iter++) { dbl_numbs [iter] = numbers.poll(); } } while(token.peek()!=null) { temp_token = token.peek(); token.poll(); if(temp_token== '+') { eval_inner_add(dbl_numbs, numbers_sz); results = eval_inner_add(dbl_numbs,numbers_sz); } else if(temp_token == '-') { eval_inner_add(dbl_numbs, numbers_sz); } else if(temp_token == '*') { results = eval_inner_multi(dbl_numbs, numbers_sz); } else if(temp_token == '/') { eval_inner_div(dbl_numbs, numbers_sz); } } return t_vals; } //-----------------Removing---Brackets-------------------------------------------------------------// public static String [] remove_brackets(String remove_brack) { String [] substring = remove_brack.split ("[\\[,\\]]"); String rest_of_str = substring [1]; String rest_of_str_2 = substring [2]; return new String [] {rest_of_str,rest_of_str_2}; } //-----------------Removing---Parenthesis-------------------------------------------------------------// public static String [] remove_paren(String remove_paren) { String [] substring = remove_paren.split ("[\\(,\\)]"); String rest_of_str = substring [0]; String rest_of_str_2 = substring [1]; return new String [] {rest_of_str,rest_of_str_2}; } //---------------Retrieving--Far-Left--Number----------------------------------------------------// public static double get_first_exp (String get_left_exp) { double eval_num = 0; if(get_left_exp.matches("[-]")) { String [] check_neg = get_left_exp.split("[\\-]"); String neg_num = check_neg[0]; eval_num = Double.parseDouble(neg_num); eval_num = eval_num * (-1.0); return eval_num; } else { String [] parts = get_left_exp.split("[\\/,\\*,\\+]"); String sub_str_1 = parts [0]; eval_num = Double.parseDouble(sub_str_1); return eval_num; } } //-------------Evaluating--equations--containing--sine----------------------------------------// public static double eval_sin (String sin_eq) { double number = 0; String [] split = remove_paren(sin_eq); String inner_exp = split[1]; double [] nothing = new double [0]; number = get_first_exp (sin_eq); queue_str(inner_exp, nothing); return number; } //-------------Evaluating--equations--containing--cosine----------------------------------------// public static double eval_cos (String cos_eq) { double number = 0; double [] nothing = new double [0]; String [] split = remove_paren(cos_eq); String inner_exp = split[1]; number = get_first_exp (cos_eq); queue_str(inner_exp, nothing); return number; } //---------------Evalutating--points-------------------------------------------------------------// public static double[] eval_inner_multi (double [] numbers, int numbers_sz) { String nothing = ""; double[] results = new double [numbers_sz]; double first_num = numbers[0]; System.out.println(first_num); for(int i = 1; i < numbers_sz-1; i++) { results[i] = first_num * numbers[i]; System.out.println(results[i]); } queue_str(nothing,results); return results; } public static double[] eval_inner_add (double [] numbers, int numbers_sz) { String nothing = ""; double[] results = new double [numbers_sz]; double first_num = numbers[0]; for(int i = 1; i < numbers_sz-1; i++) { results[i] = first_num + numbers[i]; System.out.println(results[i]); } queue_str(nothing,results); return results; } public static double[] eval_inner_sub(double [] numbers, int numbers_sz) { double[] t_vals = new double [5]; return t_vals; } public static double[] eval_inner_div(double [] numbers,int numbers_sz) { double[] t_vals = new double [5]; return t_vals; } //------------------------------Main------------------------------------------------------------------------// public static void main(String[] args) { String left_exp = ""; String right_exp = ""; double left_sin_num , right_sin_num, left_cos_num, right_cos_num = 0; for(String s: args) // taking in user input for command line { String [] new_str = remove_brackets(s); left_exp = new_str[0]; right_exp = new_str[1]; } if(left_exp.contains("sin")) // add SINE, SIN, COSINE, COS { left_sin_num = eval_sin(left_exp); } else if (right_exp.contains("sin")) { right_sin_num = eval_sin(right_exp); } if (right_exp.contains("cos")) { right_cos_num = eval_cos(right_exp); } else if (left_exp.contains("cos")) { left_cos_num = eval_cos(left_exp); } } ``` } The purpose of this assignment was to create a program that evaluates parametric equations and joins the coordinates for plotting a graph. The problem that i have is when i send my array of doubles in the queue_str() function to get evaluated, the instance where i have two operations present stumps we. I cannot properly send the contents back to the queue_str() to be evaluated by the second operand for example take into account the example function in my top comments i am able to send 3*t where t_vals are test cases to be multiplied by the three. In this case i have to go size of array -1 because i have to take into account the first and last element in the array. This is where im stuck how can I properly evaluate this expression? I would appreciate any help and i apologize for this paragraph, i just know im so close to getting this to work. Thanks.