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These are questions asked by Cata

Hello everyone,

I am trying to solve a system of 4 ODEs that describe a physical system, however, I get the message:

Error, (in dsolve/numeric/bvp) matrix is singular

Any help is much appreciated. The initial conditions are such that to find solution in steady state, that means, v(0)=v(period) and so on with all variables.


Hello everyone,

I want to solve a simple ODE numerically having a piecewise periodic function in the ODE.

The periodic piecewise function definition is taken from this  post.

When solving using "dsolve" numerical, I get this error:

Error, (in f) unable to store '100000*square_wave_periodic' when datatype=float[8]

d := .5;
fs := 100*10^3;
Vin := 10;
C := 10*10^(-6);
R := 10;
L := 10*10^(-6);

square_wave := proc (t) options operator, arrow; piecewise(0 <= t and t <= d/fs, Vin, d/fs < t and t < 1/fs, 0) end proc

square_wave_periodic := proc (t) options operator, arrow; square_wave(t-floor(t*fs)/fs) end proc

ode1 := L*(diff(i(t), t))+v(t) = square_wave_periodic
ode2 := C*(diff(v(t), t))+v(t)/R = i(t)
IC := v(0) = 0, i(0) = 0
sol := dsolve({IC, ode1, ode2}, {i(t), v(t)}, numeric)

Any help is much appreciated ! Thank you !

Hello everyone,

I am trying to solve a simple nonlinear 4 variable function with NLPsolve giving real values ranges for the variables but the NLPsolve gives "non numerical" result. Find attached the

Am I doing something wrong?



Hello everyone,

I am trying to solve an equation using the "solve(...)" function but the coefficients of the equation are changing.

I am using the coefficients as list but the "solve(...)" function gives error: "Error, (in assuming) when calling 'Engine:-Dispatch'. Received: 'badly formed input to solve: not fully algebraic'"

I am attaching the Maple document.


However, what I want to achieve, is the solution for each value in the list.

Here is an easy example of what I am saying:

a=3*x+k where k=[list of values], a=[another list of values].

I want to find "x" for each pair of values (a,k) in the list.


Thank you !



LCC Resonant Converter - Frequency Finder





V__out := 50.0

`&omega;__line` := 2.0*Pi*50

t := [seq(0 .. 10*10^(-3), .1*10^(-3))]

theta := `&omega;__line`*t

v__line := 85*sqrt(2.0)*`~`[sin](theta)

m := 1

Q__s := 3.2*`~`[`^`](`~`[sin](theta), 2)


f__n := `assuming`([solve((1/120)*V__out = 1/sqrt((-m*x^2+m+1)^2+(Q__s*(x-1/x))^2), x, useassumptions)], [x::positive])

Error, (in assuming) when calling 'Engine:-Dispatch'. Received: 'badly formed input to solve: not fully algebraic'





Hello everybody,

I am trying to solve the following integral which also has summation but it gives me strange results. Do anyone know if I am doing something wrong?

The equation is in black and the strange result is in blue.

Thank you !

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