Zachary Russell / Mbed 2 deprecated mbedica

Mathematica-like environment on the mbed using USB keyboard input, VGA output, and a thermal printer.

Dependencies:   mbed Thermal 4DGL-uLCD-SE USBHost_Modified uVGAIII

tree.c@6:646d22295054, 2018-12-13 (annotated)

Committer:
zrussell3
Date:
Thu Dec 13 20:27:21 2018 +0000
Revision:
6:646d22295054
Implemented parsing

Who changed what in which revision?

UserRevisionLine numberNew contents of line
zrussell3 6:646d22295054 1 #include "tree.h"
zrussell3 6:646d22295054 2 #include <stdlib.h>
zrussell3 6:646d22295054 3 #include <stdio.h>
zrussell3 6:646d22295054 4 #include <math.h>
zrussell3 6:646d22295054 5 #include <string.h>
zrussell3 6:646d22295054 6
zrussell3 6:646d22295054 7 /* Returns a string for each type of operator */
zrussell3 6:646d22295054 8 float eval_node(struct node* node, int level);
zrussell3 6:646d22295054 9 void set_number_node(struct node* node, float num);
zrussell3 6:646d22295054 10
zrussell3 6:646d22295054 11 /* local variables */
zrussell3 6:646d22295054 12 struct node* expr_root_node;
zrussell3 6:646d22295054 13 float Xvalue;
zrussell3 6:646d22295054 14
zrussell3 6:646d22295054 15 float eval_expr(struct node* node, float x_value) {
zrussell3 6:646d22295054 16 Xvalue = x_value;
zrussell3 6:646d22295054 17 return eval_node(node, 0);
zrussell3 6:646d22295054 18 }
zrussell3 6:646d22295054 19
zrussell3 6:646d22295054 20 float p(float l) {
zrussell3 6:646d22295054 21 // printf(" op val: %g\n", l);
zrussell3 6:646d22295054 22 return l;
zrussell3 6:646d22295054 23 }
zrussell3 6:646d22295054 24
zrussell3 6:646d22295054 25 float eval_op (struct node* op, int level) {
zrussell3 6:646d22295054 26 float right = eval_node(op->right, level+1);
zrussell3 6:646d22295054 27 float left = eval_node(op->left, level+1);
zrussell3 6:646d22295054 28
zrussell3 6:646d22295054 29 switch(op->data.op) {
zrussell3 6:646d22295054 30 case OP_ADD: return p(left + right);
zrussell3 6:646d22295054 31 case OP_SUB: return p(left - right);
zrussell3 6:646d22295054 32 case OP_MUL: return p(left * right);
zrussell3 6:646d22295054 33 case OP_DIV: return p(left / right);
zrussell3 6:646d22295054 34 case OP_EXP: return p(pow(left,right));
zrussell3 6:646d22295054 35 default:
zrussell3 6:646d22295054 36 fprintf(stderr, "%d not defined as an operator in decode_op_type\n", op->data.op);
zrussell3 6:646d22295054 37 exit(1);
zrussell3 6:646d22295054 38 }
zrussell3 6:646d22295054 39
zrussell3 6:646d22295054 40 }
zrussell3 6:646d22295054 41
zrussell3 6:646d22295054 42 void set_root_node(struct node* node) {
zrussell3 6:646d22295054 43 expr_root_node = node;
zrussell3 6:646d22295054 44 }
zrussell3 6:646d22295054 45
zrussell3 6:646d22295054 46 float eval_node(struct node* node, int level) {
zrussell3 6:646d22295054 47 switch(node->type) {
zrussell3 6:646d22295054 48 case NODE_NUMBER:
zrussell3 6:646d22295054 49 return node->data.fval;
zrussell3 6:646d22295054 50
zrussell3 6:646d22295054 51 case NODE_VAR:
zrussell3 6:646d22295054 52 // printf("eval var x: %s\n",node->data.name);
zrussell3 6:646d22295054 53 // printf("eval var x: %d\n",node->type);
zrussell3 6:646d22295054 54 // printf("eval var x: %g\n",node->data.fval);
zrussell3 6:646d22295054 55 if (strcmp(node->data.name,"x")==0) {
zrussell3 6:646d22295054 56 return Xvalue;
zrussell3 6:646d22295054 57 } else {
zrussell3 6:646d22295054 58 fprintf(stderr,"Cannot parse variables: %s\n", node->data.name);
zrussell3 6:646d22295054 59 exit(1);
zrussell3 6:646d22295054 60 }
zrussell3 6:646d22295054 61
zrussell3 6:646d22295054 62 case NODE_BINOP:
zrussell3 6:646d22295054 63 return eval_op(node, level+1);
zrussell3 6:646d22295054 64
zrussell3 6:646d22295054 65 case NODE_FUNC:
zrussell3 6:646d22295054 66 if (strcmp(node->data.name,"sin")==0) {
zrussell3 6:646d22295054 67 printf("Calling function: sin(...)\n");
zrussell3 6:646d22295054 68 float y = eval_node(node->left, level+1);
zrussell3 6:646d22295054 69 return sin(y);
zrussell3 6:646d22295054 70 }
zrussell3 6:646d22295054 71 if (strcmp(node->data.name,"cos")==0) {
zrussell3 6:646d22295054 72 printf("Calling function: cos(...)\n");
zrussell3 6:646d22295054 73 float y = eval_node(node->left, level+1);
zrussell3 6:646d22295054 74 return cos(y);
zrussell3 6:646d22295054 75 }
zrussell3 6:646d22295054 76 if (strcmp(node->data.name,"tan")==0) {
zrussell3 6:646d22295054 77 printf("Calling function: tan(...)\n");
zrussell3 6:646d22295054 78 float y = eval_node(node->left, level+1);
zrussell3 6:646d22295054 79 return tan(y);
zrussell3 6:646d22295054 80 }
zrussell3 6:646d22295054 81 }
zrussell3 6:646d22295054 82
zrussell3 6:646d22295054 83 exit(1);
zrussell3 6:646d22295054 84 }
zrussell3 6:646d22295054 85
zrussell3 6:646d22295054 86
zrussell3 6:646d22295054 87 struct node* new_number_node(float num){
zrussell3 6:646d22295054 88 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 89 node->type = NODE_NUMBER;
zrussell3 6:646d22295054 90 node->data.fval = num;
zrussell3 6:646d22295054 91 node->left = NULL;
zrussell3 6:646d22295054 92 node->right = NULL;
zrussell3 6:646d22295054 93 node->parent = NULL;
zrussell3 6:646d22295054 94 return node;
zrussell3 6:646d22295054 95 }
zrussell3 6:646d22295054 96
zrussell3 6:646d22295054 97
zrussell3 6:646d22295054 98 struct node* new_var_node(char* str){
zrussell3 6:646d22295054 99 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 100 node->type = NODE_VAR;
zrussell3 6:646d22295054 101 node->data.name = str;
zrussell3 6:646d22295054 102 node->left = NULL;
zrussell3 6:646d22295054 103 node->right = NULL;
zrussell3 6:646d22295054 104 node->parent = NULL;
zrussell3 6:646d22295054 105 return node;
zrussell3 6:646d22295054 106 }
zrussell3 6:646d22295054 107
zrussell3 6:646d22295054 108
zrussell3 6:646d22295054 109 struct node* new_binop_node(enum op_type op, struct node* left, struct node *right){
zrussell3 6:646d22295054 110 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 111 node->type = NODE_BINOP;
zrussell3 6:646d22295054 112 node->data.op = op;
zrussell3 6:646d22295054 113 node->left = left;
zrussell3 6:646d22295054 114 node->left->parent = node;
zrussell3 6:646d22295054 115 node->right = right;
zrussell3 6:646d22295054 116 node->right->parent = node;
zrussell3 6:646d22295054 117 node->parent = NULL;
zrussell3 6:646d22295054 118 return node;
zrussell3 6:646d22295054 119 }
zrussell3 6:646d22295054 120
zrussell3 6:646d22295054 121 struct node* new_binop_node_no_right(enum op_type op, struct node* left){
zrussell3 6:646d22295054 122 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 123 node->type = NODE_BINOP;
zrussell3 6:646d22295054 124 node->data.op = op;
zrussell3 6:646d22295054 125 node->left = left;
zrussell3 6:646d22295054 126 node->left->parent = node;
zrussell3 6:646d22295054 127 node->right = NULL;
zrussell3 6:646d22295054 128 node->parent = NULL;
zrussell3 6:646d22295054 129 return node;
zrussell3 6:646d22295054 130 }
zrussell3 6:646d22295054 131
zrussell3 6:646d22295054 132 struct node* new_func_node(char* name, struct node* left){
zrussell3 6:646d22295054 133 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 134 node->type = NODE_FUNC;
zrussell3 6:646d22295054 135 node->data.name = name;
zrussell3 6:646d22295054 136 node->left = left;
zrussell3 6:646d22295054 137 node->left->parent = node;
zrussell3 6:646d22295054 138 node->right = NULL;
zrussell3 6:646d22295054 139 node->parent = NULL;
zrussell3 6:646d22295054 140 return node;
zrussell3 6:646d22295054 141 }
zrussell3 6:646d22295054 142
zrussell3 6:646d22295054 143 struct node* new_func_node_no_left(char* name) {
zrussell3 6:646d22295054 144 struct node* node = calloc(sizeof(*node),1);
zrussell3 6:646d22295054 145 node->type = NODE_FUNC;
zrussell3 6:646d22295054 146 node->data.name = name;
zrussell3 6:646d22295054 147 node->left = NULL;
zrussell3 6:646d22295054 148 node->right = NULL;
zrussell3 6:646d22295054 149 node->parent = NULL;
zrussell3 6:646d22295054 150 return node;
zrussell3 6:646d22295054 151 }
zrussell3 6:646d22295054 152
zrussell3 6:646d22295054 153 // Try to match a number token
zrussell3 6:646d22295054 154 // >0 success
zrussell3 6:646d22295054 155 // 0 no match
zrussell3 6:646d22295054 156 // -1 syntax error
zrussell3 6:646d22295054 157 int isNumber(const char* expr) {
zrussell3 6:646d22295054 158 int len = strlen(expr);
zrussell3 6:646d22295054 159 int num_of_dots = 0;
zrussell3 6:646d22295054 160 int i =0;
zrussell3 6:646d22295054 161
zrussell3 6:646d22295054 162 for (int i=0; i<len; i++) {
zrussell3 6:646d22295054 163 switch(expr[i]) {
zrussell3 6:646d22295054 164
zrussell3 6:646d22295054 165 // find digit, '.'
zrussell3 6:646d22295054 166 case '0' ... '9':
zrussell3 6:646d22295054 167 continue;
zrussell3 6:646d22295054 168 case '.':
zrussell3 6:646d22295054 169 num_of_dots++;
zrussell3 6:646d22295054 170 if (num_of_dots>1)
zrussell3 6:646d22295054 171 return -num_of_dots; // an error
zrussell3 6:646d22295054 172 continue;
zrussell3 6:646d22295054 173
zrussell3 6:646d22295054 174 // legal end of match
zrussell3 6:646d22295054 175 case ' ' :
zrussell3 6:646d22295054 176 case '\t':
zrussell3 6:646d22295054 177 case '\n':
zrussell3 6:646d22295054 178 case '(' :
zrussell3 6:646d22295054 179 case ')' :
zrussell3 6:646d22295054 180 case '+' :
zrussell3 6:646d22295054 181 case '-' :
zrussell3 6:646d22295054 182 case '*' :
zrussell3 6:646d22295054 183 case '/' :
zrussell3 6:646d22295054 184 case '^' :
zrussell3 6:646d22295054 185 return i;
zrussell3 6:646d22295054 186
zrussell3 6:646d22295054 187 // error end of match
zrussell3 6:646d22295054 188 default:
zrussell3 6:646d22295054 189 return -i;
zrussell3 6:646d22295054 190 }
zrussell3 6:646d22295054 191 }
zrussell3 6:646d22295054 192 return i;
zrussell3 6:646d22295054 193 }
zrussell3 6:646d22295054 194
zrussell3 6:646d22295054 195 int isFunc(const char* expr) {
zrussell3 6:646d22295054 196 for (int i=0; i<strlen(expr); i++) {
zrussell3 6:646d22295054 197 switch(expr[i]) {
zrussell3 6:646d22295054 198 case 'a' ... 'z':
zrussell3 6:646d22295054 199 case 'A' ... 'Z':
zrussell3 6:646d22295054 200 case '_':
zrussell3 6:646d22295054 201 continue;
zrussell3 6:646d22295054 202 case '(':
zrussell3 6:646d22295054 203 return i;
zrussell3 6:646d22295054 204 default:
zrussell3 6:646d22295054 205 return i==0 ? -1 : -i;
zrussell3 6:646d22295054 206 }
zrussell3 6:646d22295054 207 }
zrussell3 6:646d22295054 208 return -1;
zrussell3 6:646d22295054 209 }
zrussell3 6:646d22295054 210
zrussell3 6:646d22295054 211 int isVar(const char* expr) {
zrussell3 6:646d22295054 212 if (strlen(expr)==0)
zrussell3 6:646d22295054 213 return 0;
zrussell3 6:646d22295054 214
zrussell3 6:646d22295054 215 for (int i=0; i<strlen(expr); i++) {
zrussell3 6:646d22295054 216 // match var name
zrussell3 6:646d22295054 217 switch(expr[i]) {
zrussell3 6:646d22295054 218 case 'a' ... 'z':
zrussell3 6:646d22295054 219 case 'A' ... 'Z':
zrussell3 6:646d22295054 220 case '_':
zrussell3 6:646d22295054 221 continue;
zrussell3 6:646d22295054 222
zrussell3 6:646d22295054 223 // match terminating character
zrussell3 6:646d22295054 224 case ' ' :
zrussell3 6:646d22295054 225 case '\t':
zrussell3 6:646d22295054 226 case '\n':
zrussell3 6:646d22295054 227 case ')' :
zrussell3 6:646d22295054 228 case '+' :
zrussell3 6:646d22295054 229 case '-' :
zrussell3 6:646d22295054 230 case '*' :
zrussell3 6:646d22295054 231 case '/' :
zrussell3 6:646d22295054 232 case '^' :
zrussell3 6:646d22295054 233 return i;
zrussell3 6:646d22295054 234 default:
zrussell3 6:646d22295054 235 return i==0 ? -1 : -i;
zrussell3 6:646d22295054 236 }
zrussell3 6:646d22295054 237 }
zrussell3 6:646d22295054 238 return -1;
zrussell3 6:646d22295054 239 }
zrussell3 6:646d22295054 240
zrussell3 6:646d22295054 241 // Add right side of OP
zrussell3 6:646d22295054 242 struct node* add_right(struct node* node, struct node* right){
zrussell3 6:646d22295054 243 node->right = right;
zrussell3 6:646d22295054 244 right->parent = node;
zrussell3 6:646d22295054 245 return right;
zrussell3 6:646d22295054 246 }
zrussell3 6:646d22295054 247
zrussell3 6:646d22295054 248 // Add right side of OP
zrussell3 6:646d22295054 249 struct node* add_left(struct node* node, struct node* left){
zrussell3 6:646d22295054 250 node->left = left;
zrussell3 6:646d22295054 251 left->parent = node;
zrussell3 6:646d22295054 252 return left;
zrussell3 6:646d22295054 253 }
zrussell3 6:646d22295054 254
zrussell3 6:646d22295054 255 // Add a Node
zrussell3 6:646d22295054 256 struct node* add_op(struct node* left, enum op_type op) {
zrussell3 6:646d22295054 257 struct node* binop = NULL;
zrussell3 6:646d22295054 258 struct node* parent = NULL;
zrussell3 6:646d22295054 259
zrussell3 6:646d22295054 260 // no precedence ordering required
zrussell3 6:646d22295054 261 if (left->parent==NULL) {
zrussell3 6:646d22295054 262 return new_binop_node_no_right(op, left);
zrussell3 6:646d22295054 263 }
zrussell3 6:646d22295054 264
zrussell3 6:646d22295054 265 // new operation is same or higher precedence, so append as child of branch
zrussell3 6:646d22295054 266 if (op >= left->parent->data.op) {
zrussell3 6:646d22295054 267 parent = left->parent;
zrussell3 6:646d22295054 268 binop = new_binop_node_no_right(op, left);
zrussell3 6:646d22295054 269 add_right(parent, binop);
zrussell3 6:646d22295054 270 return binop;
zrussell3 6:646d22295054 271 }
zrussell3 6:646d22295054 272
zrussell3 6:646d22295054 273 // traverse up the tree until no more parents or parent operation is lower precedence
zrussell3 6:646d22295054 274 return add_op(left->parent, op);
zrussell3 6:646d22295054 275 }
zrussell3 6:646d22295054 276
zrussell3 6:646d22295054 277 // scanner and parser
zrussell3 6:646d22295054 278 struct node* scanner(const char* es) {
zrussell3 6:646d22295054 279 char buff[200];
zrussell3 6:646d22295054 280 int len = strlen(es);
zrussell3 6:646d22295054 281 struct node* left = NULL;
zrussell3 6:646d22295054 282 int lookahead = -1; // 0: fails, >0: success
zrussell3 6:646d22295054 283
zrussell3 6:646d22295054 284 for (int i=0; i<len; i++) {
zrussell3 6:646d22295054 285
zrussell3 6:646d22295054 286 switch(es[i]) {
zrussell3 6:646d22295054 287 // skip space
zrussell3 6:646d22295054 288 case ' ' : continue; // printf("[space]");
zrussell3 6:646d22295054 289 case '\t': continue; // printf("[tab]");
zrussell3 6:646d22295054 290 case '\n': continue; // printf("[newline]");
zrussell3 6:646d22295054 291
zrussell3 6:646d22295054 292 // find number
zrussell3 6:646d22295054 293 case '0' ... '9':
zrussell3 6:646d22295054 294 case '.':
zrussell3 6:646d22295054 295 lookahead = isNumber(&es[i+1]);
zrussell3 6:646d22295054 296 if (lookahead>=0) {
zrussell3 6:646d22295054 297 memcpy(buff, &es[i], lookahead+1);
zrussell3 6:646d22295054 298 buff[lookahead+1] = (char) 0;
zrussell3 6:646d22295054 299 i = i + lookahead;
zrussell3 6:646d22295054 300 // printf("token-number: '%s' (atof:%f)\n", buff,atof(buff));
zrussell3 6:646d22295054 301
zrussell3 6:646d22295054 302 if (left==NULL) {
zrussell3 6:646d22295054 303 left = new_number_node(atof(buff));
zrussell3 6:646d22295054 304 } else if (left->type==NODE_BINOP) {
zrussell3 6:646d22295054 305 left = add_right(left, new_number_node(atof(buff)));
zrussell3 6:646d22295054 306 } else if (left->type==NODE_FUNC) {
zrussell3 6:646d22295054 307 left = add_left(left, new_number_node(atof(buff)));
zrussell3 6:646d22295054 308 left = left->parent;
zrussell3 6:646d22295054 309 }
zrussell3 6:646d22295054 310 }
zrussell3 6:646d22295054 311 continue;
zrussell3 6:646d22295054 312
zrussell3 6:646d22295054 313 // operators
zrussell3 6:646d22295054 314 case '+' :
zrussell3 6:646d22295054 315 // printf("token-add: '%c'\n", es[i]);
zrussell3 6:646d22295054 316 left = add_op(left, OP_ADD);
zrussell3 6:646d22295054 317 continue;
zrussell3 6:646d22295054 318 case '-' :
zrussell3 6:646d22295054 319 // printf("token-sub: '%c'\n", es[i]);
zrussell3 6:646d22295054 320 left = add_op(left, OP_SUB);
zrussell3 6:646d22295054 321 continue;
zrussell3 6:646d22295054 322 case '*' :
zrussell3 6:646d22295054 323 // printf("token-mul: '%c'\n", es[i]);
zrussell3 6:646d22295054 324 left = add_op(left, OP_MUL);
zrussell3 6:646d22295054 325 continue;
zrussell3 6:646d22295054 326 case '/' :
zrussell3 6:646d22295054 327 // printf("token-div: '%c'\n", es[i]);
zrussell3 6:646d22295054 328 left = add_op(left, OP_DIV);
zrussell3 6:646d22295054 329 continue;
zrussell3 6:646d22295054 330 case '^' :
zrussell3 6:646d22295054 331 // printf("token-exp: '%c'\n", es[i]);
zrussell3 6:646d22295054 332 left = add_op(left, OP_EXP);
zrussell3 6:646d22295054 333 continue;
zrussell3 6:646d22295054 334
zrussell3 6:646d22295054 335 case 'a' ... 'z':
zrussell3 6:646d22295054 336 case 'A' ... 'Z':
zrussell3 6:646d22295054 337 // find function
zrussell3 6:646d22295054 338 lookahead = isFunc(&es[i+1]);
zrussell3 6:646d22295054 339 if (lookahead>=0) {
zrussell3 6:646d22295054 340 memcpy(buff, &es[i], lookahead+1);
zrussell3 6:646d22295054 341 buff[lookahead+1] = (char) 0;
zrussell3 6:646d22295054 342 printf("token-func: '%s'\n", buff);
zrussell3 6:646d22295054 343 i = i + lookahead;
zrussell3 6:646d22295054 344 /*
zrussell3 6:646d22295054 345 if (left==NULL) {
zrussell3 6:646d22295054 346 left = new_func_node(buff);
zrussell3 6:646d22295054 347 } else if (left->type==NODE_BINOP) {
zrussell3 6:646d22295054 348 left = add_right(left, new_func_node(buff));
zrussell3 6:646d22295054 349 }
zrussell3 6:646d22295054 350 */ continue;
zrussell3 6:646d22295054 351 }
zrussell3 6:646d22295054 352
zrussell3 6:646d22295054 353 // find variable
zrussell3 6:646d22295054 354 lookahead = isVar(&es[i+1]);
zrussell3 6:646d22295054 355 if (lookahead>=0) {
zrussell3 6:646d22295054 356 memcpy(buff, &es[i], lookahead+1);
zrussell3 6:646d22295054 357 buff[lookahead+1] = (char) 0;
zrussell3 6:646d22295054 358 // printf("token-var: '%s'\n", buff);
zrussell3 6:646d22295054 359 i = i + lookahead;
zrussell3 6:646d22295054 360
zrussell3 6:646d22295054 361 if (left==NULL) {
zrussell3 6:646d22295054 362 left = new_var_node(buff);
zrussell3 6:646d22295054 363 } else if (left->type==NODE_BINOP) {
zrussell3 6:646d22295054 364 left = add_right(left, new_var_node(buff));
zrussell3 6:646d22295054 365 }
zrussell3 6:646d22295054 366 continue;
zrussell3 6:646d22295054 367 }
zrussell3 6:646d22295054 368
zrussell3 6:646d22295054 369 // grouping
zrussell3 6:646d22295054 370 case '(' :
zrussell3 6:646d22295054 371 printf("token-l-paren: '%c'\n", es[i]);
zrussell3 6:646d22295054 372 continue;
zrussell3 6:646d22295054 373 case ')' :
zrussell3 6:646d22295054 374 printf("token-r-paren: '%c'\n", es[i]);
zrussell3 6:646d22295054 375 continue;
zrussell3 6:646d22295054 376
zrussell3 6:646d22295054 377
zrussell3 6:646d22295054 378 default: ;
zrussell3 6:646d22295054 379 }
zrussell3 6:646d22295054 380 }
zrussell3 6:646d22295054 381
zrussell3 6:646d22295054 382 // find root
zrussell3 6:646d22295054 383 while (left->parent != NULL) {
zrussell3 6:646d22295054 384 left = left->parent;
zrussell3 6:646d22295054 385 }
zrussell3 6:646d22295054 386 return left;
zrussell3 6:646d22295054 387 }
zrussell3 6:646d22295054 388
zrussell3 6:646d22295054 389
zrussell3 6:646d22295054 390
zrussell3 6:646d22295054 391 /*
zrussell3 6:646d22295054 392 static const char expr_str[] = "5*4 * 3 / 2 - 1 + 37\n";
zrussell3 6:646d22295054 393
zrussell3 6:646d22295054 394 // compile expression
zrussell3 6:646d22295054 395 struct node* expr = comp_expr(expr_str);
zrussell3 6:646d22295054 396
zrussell3 6:646d22295054 397 // evaluate expression
zrussell3 6:646d22295054 398 eval_expr(expr, 1);
zrussell3 6:646d22295054 399
zrussell3 6:646d22295054 400 // some output
zrussell3 6:646d22295054 401 printf("Expression: %s\n", expr_str);
zrussell3 6:646d22295054 402 x = 3.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 403 x = 3.5; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 404 x = 4.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 405
zrussell3 6:646d22295054 406 // example 2
zrussell3 6:646d22295054 407 static const char str2[] = "5*4 * 3 / 2 - x + 37\n";
zrussell3 6:646d22295054 408 expr = comp_expr(str2);
zrussell3 6:646d22295054 409 eval_expr(expr, 1);
zrussell3 6:646d22295054 410
zrussell3 6:646d22295054 411 printf("Expression: %s\n", str2);
zrussell3 6:646d22295054 412 x = 1.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 413 x = 3.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 414 x = 3.5; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 415 x = 4.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 416
zrussell3 6:646d22295054 417
zrussell3 6:646d22295054 418 // example 3
zrussell3 6:646d22295054 419 static const char str3[] = "5*4 * 3 / 2 - 1 + 37 + sin(x)\n";
zrussell3 6:646d22295054 420 expr = comp_expr(str3);
zrussell3 6:646d22295054 421 eval_expr(expr, 1);
zrussell3 6:646d22295054 422
zrussell3 6:646d22295054 423 printf("Expression: %s\n", str3);
zrussell3 6:646d22295054 424 x =-1.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 425 x = 1.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 426 x = 3.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 427 x = 3.5; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 428 x = 4.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 429
zrussell3 6:646d22295054 430 // example 4
zrussell3 6:646d22295054 431 static const char str4[] = "5*4 * 3 / 2 - 1 + 37 + sin(x) + 2^3\n";
zrussell3 6:646d22295054 432 expr = comp_expr(str4);
zrussell3 6:646d22295054 433 eval_expr(expr, 1);
zrussell3 6:646d22295054 434
zrussell3 6:646d22295054 435 printf("Expression: %s\n", str4);
zrussell3 6:646d22295054 436 x = 1.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 437 x = 5.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 438 x = 7.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 439 x = 9.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 440 x =11.0; printf("Value[x=%2.3g]: %2.3g\n", x, eval_expr(expr, x));
zrussell3 6:646d22295054 441 */
zrussell3 6:646d22295054 442