{"ok":true,"destination":"calculator","expression":"","instructions":{"help":"/api/calc-state.php","usage":"Follow one link from \"links.keys\" to append a character, or one from \"links.actions\" to backspace/clear/calculate. Each response carries \"next\" (or, from here, \"links\") pointing at the state that reflects it — always GET that before choosing your next character. There is no token: every calculator request is a pure function of the expression= you send."},"limits":{"max_expression_length":200,"max_tokens":100,"max_nesting":20},"allowed":{"chars":["0","1","2","3","4","5","6","7","8","9",".","+","-","*","/","(",")"],"operators":["+","-","*","/"],"precedence":"standard: unary minus tightest, then * and / (left-to-right), then + and - (left-to-right); parentheses override"},"precision_notice":"Results are computed in IEEE 754 double-precision floating point (the same as PHP's native float, ~15-17 significant decimal digits) - not arbitrary-precision decimal arithmetic. Some decimal fractions cannot be represented exactly in binary, so a result may occasionally carry a tiny rounding artifact; results are rounded to 12 decimal places to hide most of this for ordinary use.","links":{"keys":{"0":"/api/calc-key.php?c=0&expression=","1":"/api/calc-key.php?c=1&expression=","2":"/api/calc-key.php?c=2&expression=","3":"/api/calc-key.php?c=3&expression=","4":"/api/calc-key.php?c=4&expression=","5":"/api/calc-key.php?c=5&expression=","6":"/api/calc-key.php?c=6&expression=","7":"/api/calc-key.php?c=7&expression=","8":"/api/calc-key.php?c=8&expression=","9":"/api/calc-key.php?c=9&expression=",".":"/api/calc-key.php?c=.&expression=","+":"/api/calc-key.php?c=%2B&expression=","-":"/api/calc-key.php?c=-&expression=","*":"/api/calc-key.php?c=%2A&expression=","/":"/api/calc-key.php?c=%2F&expression=","(":"/api/calc-key.php?c=%28&expression=",")":"/api/calc-key.php?c=%29&expression="},"actions":{"backspace":"/api/calc-action.php?do=backspace&expression=","clear":"/api/calc-action.php?do=clear&expression=","calculate":"/api/calc-action.php?do=calculate&expression="}},"see_also":{"experiment_writeup":"https://davesagenttools.com/experiment.php","get_url_endpoint":"https://davesagenttools.com/calculate","post_endpoint":"https://davesagenttools.com/calculator-post.php","keyboard":"https://davesagenttools.com/calculator.php"}}