2021-08-31 08:29:48 +0200 received badge ● Famous Question (source) 2018-09-04 20:15:10 +0200 received badge ● Notable Question (source) 2018-09-04 20:15:10 +0200 received badge ● Popular Question (source) 2018-03-20 22:05:18 +0200 received badge ● Notable Question (source) 2016-09-27 14:41:59 +0200 received badge ● Teacher (source) 2016-09-27 14:41:59 +0200 received badge ● Self-Learner (source) 2016-08-20 14:54:41 +0200 received badge ● Popular Question (source) 2016-07-04 05:55:39 +0200 commented answer numerical computation of roots (maple equivalent of fsolve) of a system of nonlinear equations with multiple variables parameters Hey thanks! Is there a way to try out multiple guesses(in an array) for multiple variables? Or any function that can do away with initial guesses or set a boundary of solutions within an interval? 2016-07-03 19:02:15 +0200 asked a question numerical computation of roots (maple equivalent of fsolve) of a system of nonlinear equations with multiple variables parameters Hi All, the following is my code: ### Begin Code##### #Parameters: k0 = 0.1 kd = 0.05 k1 = 20 j1 = 0.1 km1 = 0.2 jm1 = 0.1 k2 = 0.055 j2 = 0.1 pPTEN = 0.001 dPTEN = 0.0054 k3 = 0.006 j3 = 2 k4 = 0.15 j4 = 0.1 km4 = 73 jm4 = 0.5 pMdm2 = 0.018 dMdm2 = 0.015 dMdm2s = 0.015 k5 = 0.024 j5 = 1 k6 = 10 j6 = 0.3 km6 = 0.2 jm6 = 0.1 n1 = 3 n2 = 3 PIPtot = 1 AKTtot = 1 #Variables to solve p53 = var('p53') AKTs = var('AKTs') Mdm2 = var('Mdm2') Mdm2s = var('Mdm2s') PIP3 = var('PIP3') PTEN = var('PTEN') AKT = AKTtot - AKTs PIP2 = PIPtot - PIP3 #Rate Equations v0 = k0 v1 = (k1 * PIP3 * AKT) / (j1 + AKT) vm1 = (km1 * AKTs) / (jm1 + AKTs) v2 = (k2 * Mdm2s * p53) / (j2 + p53) v3 = (k3 * ((p53)^n1))/(((j3)^n1) + ((p53)^n1)) v4 = (k4 * PIP2)/(j4 + PIP2) vm4 = (km4 * PTEN * PIP3)/(jm4 + PIP3) v5 = (k5 * ((p53)^n2))/(((j5)^n2) + ((p53)^n2)) v6 = (k6 * Mdm2 * AKTs)/(j6 + Mdm2) vm6 = (km6 * Mdm2s)/(jm6 + Mdm2s) ss_p53 = v0 - v2 - kd*p53 ss_AKTs = v1 - vm1 ss_PIP3 = v4 - vm4 ss_PTEN = pPTEN + v3 - dPTEN * PTEN ss_Mdm2s = v6 - vm6 - dMdm2s*Mdm2s ss_Mdm2 = pMdm2 + v5 - v6 + vm6 - dMdm2*Mdm2 #Equation to Solve z = solve([ss_p53==0, ss_AKTs==0, ss_PIP3==0, ss_PTEN==0, ss_Mdm2s==0, ss_Mdm2==0],\ [p53, AKTs, PIP3,PTEN, Mdm2s, Mdm2]) End Code  I tried using Sage "solve" to analytically solve the system of equations. I got a "FloatingPointError: Floating point exception" I thought of ways to get round this exception by 1) using log and exp in my math equations -- I can't work round this 2) I have no idea how to create exceptions for this since I can't access the sub-solutions while the solutions are still underway 3)Then I tried maxima.solve --> no roots could be found Maybe, this problem can't be solved analytically, so I thought maybe I could do so numerically. Hence my following question, I can only find functions that tackle univariate equations. Is there a sage equivalent of maple's f-solve which numerically computes all roots of multivariate system of nonlinear equations without the need of initial conditions? Thanks a lot! I would really appreciate this Rgds Samantha 2016-06-30 19:37:57 +0200 received badge ● Student (source) 2016-06-30 18:02:26 +0200 asked a question why green bar disappears prematurely, my codes have not finished running Hi guys Above is my question. I have long calculations to do on Sage, however the green bar disappears, while the '/' and '\' still alternates in my webpage tab on mac safari and the solutions(graph) have yet to appear. Any idea? Thanks! Samantha 2016-06-30 17:57:42 +0200 answered a question Convert all complex numbers in array/matrix to value 0 or remove these numbers I did the following to solve this: 1) after solution and appending to lists, I stack lists into matrix 2) convert type from object to 'float64' 3) start a conditional to convert all terms with imag(x) != 0 into nan 4) do a mask to eliminate all rows(axis=1) that contains any term that gives true to isnan() 2016-06-20 03:57:42 +0200 commented question Convert all complex numbers in array/matrix to value 0 or remove these numbers 1)I did a "solve" on 2 nonlinear equations with variables var1 and var2. z = solve 2)I made 2 empty lists : var1_y = [], var2_y = [] then i appended the var 1 and var 2 solutions separately for solution in z: var1_y.append(var1.subs(solution)) var2_y.append(var2.subs(solution)) 3) then I combine them into matrix. How do I delete the rows with complex no? Thx! var1_y2 = matrix(var1_y).transpose() var2_y2 = matrix(var2)y).transpose() A = var1_y2.augment(var2_y2) [ 2 0] [ -1/10 0] [0.5186911103074608 - 0.8859791354693165I 0.1849665371636101 +0.1317620873508901I] [ 2.887006775607812 -0.1147163491731212 2016-06-19 17:17:17 +0200 asked a question Convert all complex numbers in array/matrix to value 0 or remove these numbers Hi all I'm new to sagemath, approximately 2 week-old. How do you convert all complex numbers in a nested array to value 0 or NaN? Or to remove these numbers from the array/matrix(which is eventually what I want to achieve in the end)? Thanks for your help! Rgds Sam