## how to plot a graph using two parameters once...

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Respected sir, I try to plot graphs using two parameters once. But it showing the error as

Error, invalid input: nops expects 1 argument, but received 2
Error, invalid input: nops expects 1 argument, but received 2
Error, invalid input: nops expects 1 argument, but received 2

can anybody do help in this regard?

## How do I obtain a numerical solution of a nonlinea...

I have a problem writing a program for the numerical solution of nonlinear volterra integral equation using the method of reproducing kernel space. I have my algorithm as well as the program I tried to write, though they are full of error messages. Please could anyone give me a clue on how to go about my challenges. The algorithm is as follows:

Step 1. Fix 𝑎 ≤ 𝑥 and 𝑡 ≤ 𝑏.
If 𝑡 ≤ 𝑥, set 𝑅𝑥(𝑡) = 1 − 𝑎 + 𝑡.
Else set 𝑅𝑥(𝑡) = 1 − 𝑎 + 𝑥.
Step 2. For 𝑖 = 1, 2, . . . , 𝑚 set 𝑥i = (𝑖 − 1)/(𝑚 − 1).

Set 𝜓i(𝑥) = 𝐿t𝑅𝑥(𝑡)|𝑡=𝑥i .
Step 3. Set 𝑢0(𝑥1) = 𝑢(𝑥1).
Step 4. For 𝑖 = 1, 2, . . . , 𝑚 set 𝛾ij = [𝜓-1]ij.
Step 5. 𝑛 = 1.
Step 6. Set Sn = Σ𝑛
𝑘=1 𝛾nk𝑢k-1(𝑥k).
Step 7. Set 𝑢n(𝑥) = Σ𝑛
𝑖=1 Si𝜓i(𝑥).
Step 8. If 𝑛 < 𝑚then set 𝑛 = 𝑛 + 1 and go to step 6.
Else stop.

## plot3d outside of an sphere?...

how can i plot outside of an sphere? for example x^2+y^2+z^2>1 ? tnx for help

## Expression not correct? Solving a system of equati...

So I have this system of equations with which I am not sure if the result is the same or not using "series" and "limit" or what is going on here.

I hope it is clear what I mean.

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## Plot Not coming for this dsolve problem...

restart;
N:=4;alpha:=5*3.14/180;r:=10;Ha:=5;H:=1;
dsolve(diff(f(x),x,x,x));
Rf:=diff(f[m-1](x),x,x,x)+2*alpha*r*sum*(f[m-1-n](x)*diff(f[n](x),x),n=0..m-1)
+(4-Ha)*(alpha)^2*diff(f[m-1](x),x);
dsolve(diff(f[m](x),x,x,x)-CHI[m]*(diff(f[m-1](x),x,x,x))=h*H*Rf,f[m](x));
f[0](x):=1-x^2;
for m from 1 by 1 to N do
CHI[m]:='if'(m>1,1,0);
f[m](x):=int(int(int(CHI[m]*(diff(f[m-1](x),x,x,x))+h*H(diff(f[m-1](x),x,x,x))
+2*h*H*alpha*r*(sum(f[m-1-n](x)*(diff(f[n](x),x)),n=0..m-1))+4*h*H*alpha^2*
(diff(f[m-1](x),x))-h*H*alpha^2*(diff(f[m-1](x),x))*Ha,x),x)+_C1*x,x)+_C2*x+_C3;
s1:=evalf(subs(x=0,f[m](x)))=0;
s2:=evalf(subs(x=0,diff(f[m](x),x)))=0;
s1:=evalf(subs(x=1,f[m](x)))=0;
s:={s1,s2,s3}:
f[m](x):=simplify(subs(solve(s,{_C1,_C2,_C3}),f[m](x)));
end do;
f(x):=sum(f[1](x),1=0..N);
hh:=evalf(subs(x=1,diff(f(x),x))):
plot(hh,h=-1.5..-0.2);
A(x):=subs(h=-0.9,f(x));
plot(A(x),x=0..1);

## How to stop myself from plotting numerical noise...

A parameterization of the function i am studying this morning produced what seems to be not single valued on the domain i choose,

plot(floor((x+1)^2/x^2)-(x+1)^2, x = -10 .. 10, coords = logarithmic);

plot(floor((x+1)^2/x^2)-(x+1)^2, x = -10 .. 10, coords = logcosh);

but the cartesian is fine:

## Problem to comapre to coefficient ...

Dear Users!

I am facing problem to compare the coefficient of x^i*y^j for i, j =1..,Equations. Please my effort and fix the problem.

H1 := 3*y^4*a[1]^5*b[1]+6*y^4*a[1]^3*b[1]^3+3*y^4*a[1]*b[1]^5+6*x*y^3*a[1]^5+6*x*y^3*a[1]^4*b[1]+12*x*y^3*a[1]^3*b[1]^2+12*x*y^3*a[1]^2*b[1]^3+6*x*y^3*a[1]*b[1]^4+6*x*y^3*b[1]^5+6*y^3*a[1]^5*b[2]+6*y^3*a[1]^4*a[2]*b[1]+12*y^3*a[1]^3*b[1]^2*b[2]+12*y^3*a[1]^2*a[2]*b[1]^3+6*y^3*a[1]*b[1]^4*b[2]+6*y^3*a[2]*b[1]^5+18*x^2*y^2*a[1]^4+36*x^2*y^2*a[1]^2*b[1]^2+18*x^2*y^2*b[1]^4+18*x*y^2*a[1]^4*a[2]+18*x*y^2*a[1]^4*b[2]+36*x*y^2*a[1]^2*a[2]*b[1]^2+36*x*y^2*a[1]^2*b[1]^2*b[2]+18*x*y^2*a[2]*b[1]^4+18*x*y^2*b[1]^4*b[2]+18*y^2*a[1]^4*a[2]*b[2]+36*y^2*a[1]^2*a[2]*b[1]^2*b[2]+18*y^2*a[2]*b[1]^4*b[2]-5*delta*y^2*a[1]^4-8*delta*y^2*a[1]^3*b[1]-10*delta*y^2*a[1]^2*b[1]^2-8*delta*y^2*a[1]*b[1]^3-5*delta*y^2*b[1]^4+12*x^3*y*a[1]^3+12*x^3*y*a[1]^2*b[1]+12*x^3*y*a[1]*b[1]^2+12*x^3*y*b[1]^3+36*x^2*y*a[1]^3*a[2]+36*x^2*y*a[1]^2*b[1]*b[2]+36*x^2*y*a[1]*a[2]*b[1]^2+36*x^2*y*b[1]^3*b[2]+18*x*y*a[1]^3*a[2]^2+36*x*y*a[1]^3*a[2]*b[2]-18*x*y*a[1]^3*b[2]^2-18*x*y*a[1]^2*a[2]^2*b[1]+36*x*y*a[1]^2*a[2]*b[1]*b[2]+18*x*y*a[1]^2*b[1]*b[2]^2+18*x*y*a[1]*a[2]^2*b[1]^2+36*x*y*a[1]*a[2]*b[1]^2*b[2]-18*x*y*a[1]*b[1]^2*b[2]^2-18*x*y*a[2]^2*b[1]^3+36*x*y*a[2]*b[1]^3*b[2]+18*x*y*b[1]^3*b[2]^2+18*y*a[1]^3*a[2]^2*b[2]-6*y*a[1]^3*b[2]^3-6*y*a[1]^2*a[2]^3*b[1]+18*y*a[1]^2*a[2]*b[1]*b[2]^2+18*y*a[1]*a[2]^2*b[1]^2*b[2]-6*y*a[1]*b[1]^2*b[2]^3-6*y*a[2]^3*b[1]^3+18*y*a[2]*b[1]^3*b[2]^2-16*delta*x*y*a[1]^3-20*delta*x*y*a[1]^2*b[1]-20*delta*x*y*a[1]*b[1]^2-16*delta*x*y*b[1]^3-10*delta*y*a[1]^3*a[2]-6*delta*y*a[1]^3*b[2]-10*delta*y*a[1]^2*a[2]*b[1]-10*delta*y*a[1]^2*b[1]*b[2]-10*delta*y*a[1]*a[2]*b[1]^2-10*delta*y*a[1]*b[1]^2*b[2]-6*delta*y*a[2]*b[1]^3-10*delta*y*b[1]^3*b[2]+12*x^4*a[1]*b[1]+12*x^3*a[1]^2*a[2]-12*x^3*a[1]^2*b[2]+24*x^3*a[1]*a[2]*b[1]+24*x^3*a[1]*b[1]*b[2]-12*x^3*a[2]*b[1]^2+12*x^3*b[1]^2*b[2]+18*x^2*a[1]^2*a[2]^2-18*x^2*a[1]^2*b[2]^2+72*x^2*a[1]*a[2]*b[1]*b[2]-18*x^2*a[2]^2*b[1]^2+18*x^2*b[1]^2*b[2]^2+6*x*a[1]^2*a[2]^3+18*x*a[1]^2*a[2]^2*b[2]-18*x*a[1]^2*a[2]*b[2]^2-6*x*a[1]^2*b[2]^3-12*x*a[1]*a[2]^3*b[1]+36*x*a[1]*a[2]^2*b[1]*b[2]+36*x*a[1]*a[2]*b[1]*b[2]^2-12*x*a[1]*b[1]*b[2]^3-6*x*a[2]^3*b[1]^2-18*x*a[2]^2*b[1]^2*b[2]+18*x*a[2]*b[1]^2*b[2]^2+6*x*b[1]^2*b[2]^3+6*a[1]^2*a[2]^3*b[2]-6*a[1]^2*a[2]*b[2]^3-3*a[1]*a[2]^4*b[1]+18*a[1]*a[2]^2*b[1]*b[2]^2-3*a[1]*b[1]*b[2]^4-6*a[2]^3*b[1]^2*b[2]+6*a[2]*b[1]^2*b[2]^3-10*delta*x^2*a[1]^2-16*delta*x^2*a[1]*b[1]-10*delta*x^2*b[1]^2-16*delta*x*a[1]^2*a[2]-4*delta*x*a[1]^2*b[2]-16*delta*x*a[1]*a[2]*b[1]-16*delta*x*a[1]*b[1]*b[2]-4*delta*x*a[2]*b[1]^2-16*delta*x*b[1]^2*b[2]-5*delta*a[1]^2*a[2]^2-6*delta*a[1]^2*a[2]*b[2]+delta*a[1]^2*b[2]^2-2*delta*a[1]*a[2]^2*b[1]-12*delta*a[1]*a[2]*b[1]*b[2]-2*delta*a[1]*b[1]*b[2]^2+delta*a[2]^2*b[1]^2-6*delta*a[2]*b[1]^2*b[2]-5*delta*b[1]^2*b[2]^2+delta^2*a[1]^2+delta^2*a[1]*b[1]+delta^2*b[1]^2+16*y^2*a[1]^2+48*y^2*a[1]*b[1]+16*y^2*b[1]^2+80*x*y*a[1]+80*x*y*b[1]+32*y*a[1]*a[2]+48*y*a[1]*b[2]+48*y*a[2]*b[1]+32*y*b[1]*b[2]+80*x^2+80*x*a[2]+80*x*b[2]+16*a[2]^2+48*a[2]*b[2]+16*b[2]^2-8*delta;

Equation := 12;

for i from 0 to Equation do;

for j from 0 to Equation do;

C[i, j] := coeff(H1, x^i*y^j) = 0;

end do;

end do;

I got this error
Error, invalid input: coeff received 1, which is not valid for its 2nd argument, x

## Indexing and storage of higher dimensional structu...

As an example, the two-dimensional Array created by

`A := Array(triangular[upper], 1..100, 1..100);`

has both indexing function and storage "triangular[upper]", which is fine. However, the attempt

`B := Array(triangular[upper], 1..100, 1..100, 1..100);`

to make a three-dimensional analogue did not work: It returns "Error, triangular[upper] indexing is only valid with 2 dimensions". A similar error message is returned when I replace "triangular[upper]" by "symmetric".

(For definiteness, by a higher-dimensional symmetric Array I would like to understand an Array with entries that are invariant under every permutation of their indices. Similarly, I would call the Array upper-triangular if only its entries with non-decreasing indices can be non-zero.)

For a first solution attempt, I mimic a higher dimensional upper-triangular Array by instead creating a multiply nested one-dimensional Array, where the one-dimensional subarrays become shorter and shorter. I did some preliminary testing with CodeTools[Usage] and the memory and timing results seem to compare favorably to naively using standard rectangular Arrays.

It seems more natural to write my own indexing function. However, I am not sure how to write a suitable corresponding storage function, as the documentation on that latter subject mentions only Vectors and Matrices. Is it possible and advisable to write my own storage function, or is there yet another more natural and memory-efficient way to store higher-dimensional structured Arrays (with symbolic data) in Maple?

Thank you very much for any insights, particularly documentation pointers.

Sebastiaan Janssens.

## Want to write an expression in sigma notation...

Dear Users!

Hope you would be fine. I want to write an expression in sigma notation which control ny n (any constant >0);
for n =1 expression expand as

E[1]+1

for n =2 expression expand as
E[1]*E[2]*a[12]+E[1]+E[2]+1;

for n =3 expression expand as

E[1]*E[2]*E[3]*a[123]+E[1]*E[2]*a[12]+E[1]*E[3]*a[13]+E[2]*E[3]*a[23]+E[1]+E[2]+E[3]+1;

for n =4 expression expand as

E[1]*E[2]*E[3]*E[4]*c[1234]+E[1]*E[2]*E[3]*a[123]+E[1]*E[2]*E[4]*a[124]+E[1]*E[3]*E[4]*a[134]+E[2]*E[3]*E[4]*a[234]+E[1]*E[2]*a[12]+E[1]*E[3]*a[13]+E[1]*E[4]*a[14]+E[2]*E[3]*a[23]+E[2]*E[4]*a[24]+E[3]*E[4]*a[34]+E[1]+E[2]+E[3]+E[4]+1;

and so on.

I am waiting your kind respons. Thanks

## Laplace transform of the product...

Hello,

how to calculate the laplace transform for the following equations?

```L1:=laplace(psi1(t)*(diff(z1(t), t)), t, s):
L2:=laplace((diff(psi1(t), t))^2, t, s):
```

## how to easily flatten a nested set?...

I can't final an equivalent to Mathematica's Flatten for sets. I know Maple has ListTools:-Flatten for lists.

For example, given set r:={a,{b,c},d,{e,f,{g,h}}}; How to convert it to  {a,b,c,d,e,f,g,h};

does one have to convert each set and all the inner sets to lists, then apply ListTools:-Flatten to the result? How to map convert(z,list) for all levels?

map(z->convert(z,list),r);

does not work, since it only maps at top level, giving {[a], [d], [b, c], [e, f, {g, h}]}

So doing

ListTools:-Flatten(convert(map(z->convert(z,list),r),list));

Gives [a, d, b, c, e, f, {g, h}]

## Trying to get permutations of letters of word...

Hey there, I'm trying to count how many letter arrangements are possible by using the algorithm below (for Maple TA). It's a bit crude but the console tells me countcharacteroccurences second argument must be a string, but it works for the earlier letters. Can someone please give me a bit of guidance?

\$temp = maple("
randomize();
with(MathML):
with(StringTools):
with(combinat):

rintS := rand(1..27);
word := ARITHMETIC,ALGORITHM,ASYMPTOTE,AVERAGE,CARTESIAN,CALCULUS,COEFFICIENT,COORDINATE,NUMERATOR,
DENOMINATOR,DIFFERENTIATE,DERIVATIVE,DIAMETER,DYNAMICS,EXTRAPOLATION,FACTORIALS,GEOMETRIC,
HYPOTENUSE,INTEGRATION,IRRATIONAL,INVERSE,ITERATION,POLYNOMIAL,COMBINATIONS,PERMUTATIONS,POLYGON;

disp := word[rintS()];
n := length(disp);

n1 := CountCharacterOccurrences(disp,A);
n2 := CountCharacterOccurrences(disp,B);
n3 := CountCharacterOccurrences(disp,C);
n4 := CountCharacterOccurrences(disp,D);
n5 := CountCharacterOccurrences(disp,E);
n6 := CountCharacterOccurrences(disp,F);
n7 := CountCharacterOccurrences(disp,G);
n8 := CountCharacterOccurrences(disp,H);
n9 := CountCharacterOccurrences(disp,I);
a1 := CountCharacterOccurrences(disp,J);
a2 := CountCharacterOccurrences(disp,K);
a3 := CountCharacterOccurrences(disp,L);
a4 := CountCharacterOccurrences(disp,M);
a5 := CountCharacterOccurrences(disp,N);
a6 := CountCharacterOccurrences(disp,O);
a7 := CountCharacterOccurrences(disp,P);
a8 := CountCharacterOccurrences(disp,Q);
a9 := CountCharacterOccurrences(disp,R);
b1 := CountCharacterOccurrences(disp,S);
b2 := CountCharacterOccurrences(disp,T);
b3 := CountCharacterOccurrences(disp,U);
b4 := CountCharacterOccurrences(disp,V);
b5 := CountCharacterOccurrences(disp,W);
b6 := CountCharacterOccurrences(disp,X);
b7 := CountCharacterOccurrences(disp,Y);
b8 := CountCharacterOccurrences(disp,Z);

z1 := n1!*n2!*n3!*n4!*n5!*n6!*n7!*n8!*n9!;
z2 := a1!*a2!*a3!*a4!*a5!*a6!*a7!*a8!*a9!;
z3 := b1!*b2!*b3!*b4!*b5!*b6!*b7!*b8!;
ans := n!/(z1*z2*z3);

Export(disp),convert(ans,string),convert(z1,string),convert(z2,string),convert(z3,string);
");

\$ans = switch(1,\$temp);
\$disp = switch(0,\$temp);

## Why does the procedure not execute?...

In attempting to store procedures in a table to create an extensible module, I used the following procedure to test whether a procedure could be queried from the table and executed.

proc() print("Metric is default") end proc;

The result was proc () print("Metric is default") end proc

I have checked the statement with mint in the code editor, but it reports no errors. I get the same result when I use an eval statement around the procedure.  I would be very interested in understanding what is wrong with the procedure as defined.

## How to select imaginary part of a solution in Mapl...

How to select imaginary part of the followig solution in Maple?

restart;
y := x^2+x+7;

A := solve({y}, {x});
/      1   3    (1/2)\    /      1   3    (1/2)\
{ x = - - + - I 3      }, { x = - - - - I 3      }
\      2   2         /    \      2   2         /
Im(A);
Error, invalid input: Im expects 1 argument, but received 2

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