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So i have a variable that is function = '(2*1)+3' how would i get it out of string form and claculate the answer? i tried using float() int(float()) but im not sure if thats for numbers only or not. I've written this a couple times, and every time it seems that I lose the code... A very simple (and "safe") calculator can be created using ast : import ast import operator _OP_MAP = { ast.Add: operator.add, ast.Sub: operator.sub, ast.Mult: operator.mul, ast.Div: operator.div, ast.Invert: operator.neg, } class Calc(ast.NodeVisitor): def visit_BinOp(self, node): left = self.visit(node.left) right =

I can not solve this expression from postfix to infix. Please help me to understand in detail 5 x y - / x y + 3 ^ 7 / + postfix to infix: 5 x y - / x y + 3 ^ 7 / + STEP 5 x y - / A) 5xy-/ = 5 (x-y)/ = (5 / (x-y)) x y + B) x y + = (x + y) (x+y) 3 ^ B.1) (x + y) 3 ^ = ((x + y) ^ 3 ) Now, (5 / (x-y)) ((x + y) ^ 3 ) 7 / + = (5 / (x-y)) (((x + y) ^ 3 )/7 ) + = (5 / (x-y)) + (((x + y) ^ 3 )/7 ) POSTFIX and PREFIX are expression in which no brackets are used. Precedence of operator are decided in order of there appearance in expression, So to evaluate expression no need to search next operation to

I'm just wondering, because the app I built does a pretty long equation, and the result is a different than when it's done on an Excel spreadsheet, where I got the equation. The difference gets higher the higher the input numbers are. Here is the equation that I entered in xcode: 360 * num1 * num3 * (1 - powf(14.9 / num1, 0.286)) (num1 and num3 are the input numbers). Here is the Excel calculation: =360*R9*R11*(1-((R10/R9)^0.286)) ( R9 is equal to num1 , and R11 is equal to num3 and R10 is 14.9) I don't see a difference in the equations, but if you do, please point it out. My quess it one of

I'm very new to python programming and to this site. I'm currently working on a problem and can't seem to understand the error. import math # Problem number 5. A5 = 5 B5 = 0 C5 = 6.5 # Root1 x9 = (-B5 + math.sqrt(B5**2 - 4*A5*C5))/(2*A5) # Root2 x10 = (-B5 + math.sqrt(B5**2 - 4*A5*C5))/(2*A5) # Print solution print() print('Problem #5') print('Root 1: ',x9) print('Root 2: ',x10) I get this after i run it: x9 = (-B5 + math.sqrt(B5**2 - 4*A5*C5))/(2*A5) ValueError: math domain error I did the problem on paper and got an answer for both... If you got an answer, it must have been a complex number

This question already has an answer here: How to evaluate formula passed as string in PHP? 2 answers So I have formula as string $comm = "(a x 5% - 2%)"; I want it to be $comm = $a * 5/100 * (1-2/100); How can I do this in php? Stuart Wakefield To do this the right way, reliably and safely, from scratch, you will need to perform: Lexical analysis, this involves pattern matching the input with tokens: (a x 5% - 2%) would become something like the following chain of tokens: openparen variable multiply integer percent minus integer percent closeparen Syntax analysis, this involves taking those