MaplePrimes - Maple 17 Posts and Questions

dolve/numeric/bvp, specify an approximate initial solution

MAXR — Wed, 11 Feb 2026 06:27:53 Z

Dear All,

I am currently encountering an issue while solving my boundary value problem in Maple. The following error message appears:
"Error, (in dsolve/numeric/bvp) cannot determine a suitable initial profile; please specify an approximate initial solution."

This problem arises when I attempt to generate plots by varying the parameters λl, λu, βl, βu, etc.

Lamda_l_new.mw

Error, (in Statistics:-Fit) invalid input: Fit expects its 4th argument, v, to be of type {name, list(name)}

MAXR — Sun, 08 Jun 2025 19:11:42 Z

Dear All, I hope this message finds you well. I am currently facing some issues and would appreciate your support or guidance in resolving them. Nusselt_RSM_Model.mw

restart;

>	with(Statistics): with(LinearAlgebra): with(plots):

>	local A, B, C, D;

>	Digits := 10:

>	# Step 1: Define the variables

>	vars := [A, B, C, D];

>	# Step 2: Generate Central Composite Design (CCD) coded matrix

>	coded := Matrix([

>	[ 1, 1, 1, 1],

>	[ 1, 1, 1, -1],

>	[ 1, 1, -1, 1],

>	[ 1, 1, -1, -1],

>	[ 1, -1, 1, 1],

>	[ 1, -1, 1, -1],

>	[ 1, -1, -1, 1],

>	[ 1, -1, -1, -1],

>	[-1, 1, 1, 1],

>	[-1, 1, 1, -1],

>	[-1, 1, -1, 1],

>	[-1, 1, -1, -1],

>	[-1, -1, 1, 1],

>	[-1, -1, 1, -1],

>	[-1, -1, -1, 1],

>	[-1, -1, -1, -1],

>	[ 0, 0, 0, 0],

>	[ 0, 0, 0, 0],

>	[ 0, 0, 0, 0],

>	[ 0, 0, 0, 0]

]):

>	# Step 3: Define uncoded variable ranges

>	rangeA := [0.1, 0.5]:

>	rangeB := [0.1, 0.5]:

>	rangeC := [0.1, 0.5]:

>	rangeD := [0.1, 0.5]:

>	decode := (val, r) -> r[1] + (val + 1)*(r[2] - r[1])/2:

>	# Step 4: Create actual values matrix

>	actual := Matrix(20, 4):

>	for i from 1 to 20 do

>	for j from 1 to 4 do

>	r := eval(cat("range", vars[j])):

>	actual[i, j] := evalf(decode(coded[i, j], r));

end do;

end do:

>	# Step 5: Define model coefficients (for simulation purposes)

>	beta := [1.5, 0.8, 0.6, 0.5, 0.3, # Linear terms

>	0.1, 0.2, 0.15, 0.18, # Square terms

>	0.05, 0.04, 0.03, 0.02, 0.01, 0.025]; # Interaction terms

>	# Step 6: Simulate Response (Nusselt number)

>	Nu := Vector(20):

>	for i from 1 to 20 do

>	A := actual[i,1]; B := actual[i,2]; C := actual[i,3]; D := actual[i,4];

>	Nu[i] := evalf(

>	beta[1] + beta[2]A + beta[3]B + beta[4]C + beta[5]D +

>	beta[6]A^2 + beta[7]B^2 + beta[8]C^2 + beta[9]D^2 +

>	beta[10]AB + beta[11]AC + beta[12]AD +

>	beta[13]BC + beta[14]BD + beta[15]CD

);

end do:

>	# Step 7: Create data frame for ANOVA

>	X := Matrix(actual):

>	Y := convert(Nu, list):

>	# Step 8: Fit quadratic model

>	model := Fit(

>	A + B + C + D + A^2 + B^2 + C^2 + D^2 + AB + AC + AD + BC + BD + CD,

vars

>	# Step 9: ANOVA table

>	anovaTable := ANOVA(model, significancelevel=0.05):

>	# Step 10: Display results with 8 decimal places

>	printf("RSM Model for Nu (Nusselt number):\n");

>	print(evalf[8](model));

>	printf("\nANOVA Table:\n");

>	print(anovaTable);

>	# Optional: Plotting

>	pointplot([seq([i, Nu[i]], i = 1..20)], style=point, symbol=circle,

>	color=red, title="Nusselt Number vs Run Index",

>	labels=["Run", "Nusselt Number"]);

Error, (in Statistics:-Fit) invalid input: Fit expects its 4th argument, v, to be of type {name, list(name)}, but received [1.5+2.2*"a"+.805*"a"^2, 1.5+1.9*"a"+.3*"r"+.56*"a"^2+.18*"r"^2+0.65e-1*"a"*"r", 1.5+1.7*"a"+.5*"r"+.57*"a"^2+.15*"r"^2+0.85e-1*"a"*"r", 1.5+1.4*"a"+.8*"r"+.35*"a"^2+.355*"r"^2+.10*"a"*"r", 1.5+1.6*"a"+.6*"r"+.525*"a"^2+.2*"r"^2+0.8e-1*"a"*"r", 1.5+1.3*"a"+.9*"r"+.29*"a"^2+.39*"r"^2+.125*"a"*"r", 1.5+1.1*"a"+1.1*"r"+.31*"a"^2+.37*"r"^2+.125*"a"*"r", 1.5+.8*"a"+1.4*"r"+.1*"a"^2+.585*"r"^2+.12*"a"*"r", 1.5+.8*"r"+1.4*"a"+.1*"r"^2+.585*"a"^2+.12*"a"*"r", 1.5+1.1*"r"+1.1*"a"+.31*"r"^2+.37*"a"^2+.125*"a"*"r", 1.5+1.3*"r"+.9*"...

RSM Model for Nu (Nusselt number):

ANOVA Table:

Error, (in plots:-pointplot) incorrect specification of points data

Download Nusselt_RSM_Model.mw

Error, attempting to assign to `D` which is protected.

MAXR — Tue, 03 Jun 2025 06:34:53 Z

Dear All,

I am facing some problems. This kind of error has been shown: "Error, attempting to assign to `D` which is protected. Try declaring `local D`; see ? protect for details."

RSM_model.mw

Another rolling without slipping

one man — Tue, 27 May 2025 15:46:05 Z

Geometrical entertainment in the form of rolling without slipping, now inside a torus.
You can also print out the corresponding equations - these graphs are # in the text, but it is better to do this separately from the geometric animation, because textplot3d takes up a lot of resources.

Please consider it not as a Maple program, but simply as an idea for a corresponding algorithm.
for_TORUS_IN_TORUS_for.mw

Error, (in plot/iplot2d/expression) bad range arguments

MAXR — Wed, 14 May 2025 11:45:04 Z

Dear All,

I am facing some problems. This kind of error has been shown ""Error, (in plot/iplot2d/expression) bad range arguments 0.3e-1 = .1 .. .5, 0.3e-1 = .1 .. .5"

Error.mw

How can I resolve the problem of asking "Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic"?

MAXR — Tue, 03 Sep 2024 11:42:57 Z

Dear All,

I am facing some problems. This kind of error has been shown "Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic"

eqn1 := {((1+1/beta).(diff(f(eta), eta, eta, eta))-(1+F[s]).((diff(f(eta), eta))^2)+(diff(f(eta), eta, eta)).f(eta)+M.(A-(diff(f(eta), eta)))-1/(R.D[a]).(diff(f(eta), eta)) = 0, diff(theta(eta), eta, eta)+4/3.N.(diff((1+(K-1).theta(eta))^3.(diff(theta(eta), eta)), eta)))+Pr.f(eta).(diff(theta(eta), eta))+(1+1/beta).Pr.Ec.((diff(f(eta), eta, eta))^2)+M.Ec.((diff(f(eta), eta)-A)^2) = 0, f(0) = 0, theta(0) = 1+alpha.(D(theta))(0), theta(10) = 0, (D(f))(0) = 1+(1+1/beta).lambda.(D(D(f)))(0), (D(f))(10) = 0};
;
sys1 := eval(eqn1, {A = 1, Ec = .2, K = 2.5, M = .5, N = .5, Pr = 6.5, R = 1, alpha = .5, beta = 2, lambda = .5, D[a] = .3, F[s] = 1});
sol1 := dsolve(sys1, numeric);
Error, (in Engine:-Dispatch) badly formed input to solve: not fully algebraic
with(plots);
t1 := odeplot(sol1, [eta, diff(f(eta), eta)], eta = 0 .. 10, numpoints = 65, thickness = 0, color = green, linestyle = solid);
plots[plots:-display]({t1})

MAXR.mw