Stephan

Last seen: Today

1.302 total contributions since 2017

Knowledge means knowing where it is written...

Interested in:
- Optimization
- Mathematical Modelling
- Improvement of my programming skills

Stephan's Badges

Answered
Fill a vector with two vectors
V1 = [3 8 6 7] V2 = [1 5 9 4] V = reshape([V1;V2],1,[]) V = V(3:end) results in: V1 = 3 8 6 7 V2 =...

21 minutos ago | 0

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Trying to plot this curve what have I done wrong?
fun = @(x)(18*sqrt(2)*(sqrt(1+1./(1+x.^2)) + asin(1./(1+x.^2)-pi/2))) fplot(fun)

alrededor de 1 hora ago | 0

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How to find the solution of inverse function ?
x = [1 2 3 4 5 6 7]; y = [3.6 1.8 1.2 0.9 0.72 1.5 0.51429]; p = polyfit(x,y,2) syms x fx(x) = poly2sym(p) gx(x) = finvers...

alrededor de 2 horas ago | 0

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Answered
Possible combinations for a vector
You could use allcomb from FEX: k = 0:2; coms = allcomb(k,k,k,k,k,k,k,k,k); as expected there are 3^9 = 19683 results

alrededor de 3 horas ago | 1

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how do i write a matlab script to sum this expression?
Symbolic: syms n positive integer N = 10000; eq = 1/n + 1/((n+2)*(n+3)); pretty(eq) sol = symsum(eq,n,1,N) sol_num = doubl...

alrededor de 5 horas ago | 1

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ODE Function time output
Use events: Z0 = 6; Zt=0.05*6; tspan = [0 24]; opts = odeset('Events',@(tZ,Z)EventsFcn(tZ,Z,Zt)); [tZ,Z,tZe,Ze,iZe] = ode45...

alrededor de 16 horas ago | 0

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Why isn't my code graph anything.
Try: %create a cater plot clear all; %x = [20,30,40,50] x = [-3,-1,1,2] y = [8,23,28,34] y=[8,23,28,34].' colum = [...

alrededor de 16 horas ago | 0

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How find symbolic solution matlab
It appears that there either is no symbolic solution or Matlab is not powerful enough to find one. For sin(t) it would work. How...

alrededor de 17 horas ago | 1

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ode 45 and for loop
k = 0; T_sol = cell(1,100); X_sol = cell(1,100); for ii = 0.1:0.1:10 k = k+1; [T,X] = ode45(@(t,x)fx(t,x,ii), [0 ...

alrededor de 23 horas ago | 0

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Graph Plotting the differential equation
yyaxis left fplot(qSol,[0, 100]) yyaxis right fplot(TSol,[0, 100])

alrededor de 23 horas ago | 1

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Answered
Defining function file of ODE function
C0 = 5; tspan = [0 10]; [t,C] = ode45(@Conc,tspan,C0); plot(t,C) function dCdt=Conc(t,C) k1=0.7; Vo=1; Q=Vo; Cin=200; ...

1 día ago | 1

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Answered
How do i plot this quadratic graph?
x = -10:10; y = polyval([1 -2 -4],x); plot(x,y) r = roots([1 -2 -4]) text(r(1),0,'\leftarrow Root') text(r(2),0,'\leftarrow...

1 día ago | 0

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Solve a Matrix equation
Symbolic approach: A = sym('A', [4,1]) B = magic(4) P = 13 sol = solve(A'*B*A==P, A) sol.A1 sol.A2 sol.A3 sol.A4 % This...

1 día ago | 0

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Suppose that at any given time t (in seconds) the current i (in amperes) in an alternating current circuit is i = 2 cos t + 2 sin t. What is the peak current for this circuit (largest magnitude)?
Do the same as shown in your question before. Then use diff(...) == 0 to find extremum points. The solve function maybe helpfu...

1 día ago | 1

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Answered
unable to find symbolic solution
1. The condition for the second ode is invalid - i assume you meant: cond = T(R)==T0; instead of cond = q(R)==T0; 2. As...

1 día ago | 1

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Answered
Find intersection point between u(t) = t^2(t-1) and u = 10.
Simply use the function you calculated: >> t_sol = vpasolve(uSol == 10,t) ans = ...

1 día ago | 1

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Answered
Error using evalin Undefined function or variable 'x'. Error in sym/eval (line 11) s = evalin('caller',vectorize(map2mat(char(x))));
clear AC=0.15; BC=0.2; AD=0.35; xA=0; yA=0; rA=[xA yA 0]; xC=AC; yC=0; rC=[xC yC 0]; syms xBsol yBsol ii=0; for ph...

1 día ago | 1

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Answered
find the equation of tangent to the curve y=2(x^1/2) at (1,2)
https://de.mathworks.com/help/symbolic/syms.html#buoeaym-1 https://de.mathworks.com/help/symbolic/diff.html

1 día ago | 1

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Answered
How to find the solution for the system of equations
Your system is inconstistent and therefore there is no solution: % x is shorter than lambda x = sym('x', [14 1]) ; % system...

1 día ago | 0

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Answered
How can I delete even rows in a matlab Matrix
>> A = [1 2 3; 4 5 6; 7 8 9; 0 -1 -2] A = 1 2 3 4 5 6 7 8 9 0 -1 -2 ...

1 día ago | 0

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Answered
ode45 Two Variable Differential equation Problem - Too many inputs error
Fixed the input in your functin. Rising t>7 gives warning, since the problem appears to be stiff: %% Initial Conditions: % Ini...

1 día ago | 0

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Answered
Graphing using Matlab. How would you graph a function using matlab?
a = 24; b = 4.8; ii = 0:20; y = a + b.*ii; plot(ii,y)

1 día ago | 0

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Please explain what this error is...
Your function has to be called with 2 inputs a and b for example when a=2 and b=5: [res1, res2, res3] = MyFun(2, 5)

3 días ago | 0

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Can anyone help me fix that error please
You missed to define several variables, which are used in your equations: % several used variables are not defined! - i set the...

4 días ago | 0

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fsolve with one variabel
Tinc = 5+273; Tinv = 45+273; mv = 1000; Cpv = 4180; A = 0.032*(21-2); h = 20; U = ...

5 días ago | 2

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Find the value which causes an error from a vector
This works with logical indexing, therefore avoids the if / else logic and should ensure that you do not need any error messages...

6 días ago | 0

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I get this error 'index in position 1 is invalid. Array indices must be positive integers or logical values.' when I am trying to store values from a for loop into a vector.
n = 9; % set the number of Monte Carlo repetitions M = 10000; % create M*1 vectors to save the realized sample statisti...

6 días ago | 0

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Answered
How to resolve the error of "Consider preallocating for speed" which is coming on executing the program below??
The answer is here: <https://de.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html>

6 días ago | 0

Answered
Solving System of two Differential Equations with one initial and one end condition
Symbolic appears to work: syms Th(x) Tc(x) m_hp = 20; m_cp = 5; cw = 1; Rw = 1; eq(1) = diff(Th,x) == -1 / ((m_hp / 2) *...

7 días ago | 1

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Answered
2 values for inputs of a function
In case of a vectorized function (yours is) you can use vector inputs: b = 5; c = [25; 60]; d = 0; [T, L] = answ(b,c,d) ...

7 días ago | 0