## Datatype error (float[8])...

I'm sorry for asking too many similar technical questions, but I just can't help this.

I'm solving a system of differential equations with dsolve and getting this type of error:

Error, (in f) unable to store 'HFloat(0.10664489706950975)+HFloat(1.1891638418458722e-5)*sin^2-HFloat(1.6095871822513048e-6)*sin' when datatype=float[8]

I checked the dsolve syntax, checked that all the constants are defined, checked that the number of equations matches the number of unknown functions (and there is no misprints of them in the code). In brief, I checked all the stuff that I usually have mistakes in, and yet the error stands.

Here's the file: 1.mw

## cannot find the error in loop...

cannot find the error in loop

> restart; u[0] := (4/3)*c^2*cos((1/4)*x)^2; alpha := 2;

> iteration := 3;
> for k from 0 while k <= Iteration do u[s] := eval(u[k], t = xi); u[k+1] := simplify(u[k]-(int(diff(u[s], [`\$`(xi, alpha)])+diff(u[s]*u[s], x)+diff(u[s]*u[s], x, x, x), xi = 0 .. t))) end do;

## solve using assume option...

how can solve using assume option ?

 > restart:
 > F(z):=m*z^4-4*m*z^3+(3*m+3)*z^2-6*u;
 (1)
 > solve(F(z),z assuming -0.5
 >

## Computing the Sine and Cosine Funtion...

Hi,

When I type sin(pi/2) the result is sin(pi/2) (not "1.0)

What should I do to get "1.0" instead of replicating the sin(pi/2) ?!

I mean why the expression contating "pi" can not being simplified?

Is there any solution to this problem?

Thanks

## Iterated Functions...

how are iterated functions represented in maple? as in f(f(f(x))) is (x)  in conventional notation where by the reader knows it is refering to the iteration conducted 3 times on the argument x, but what does maple use to differentiate between iteration ,exponentiation and differentiation?

## how do I solve an algebra problem with an exp...

I have a simple algebraic problem, but Maple can't eliminate the exp(3P) in each term. Please help.

I get the following error:

Error, (in solve) cannot solve for an unknown function with other operations in its arguments

 (1)

 (2)

 (3)

 (4)

 (5)

 (6)

 (7)

 (8)

 (9)

 (10)

 (11)

 (12)

## why "end proc();" do not generate an error?...

when writing by error the following

restart;
f:=proc()
dsolve(diff(y(x),x)+y(x)=0,y(x));
end proc();

Maple did not complain and returned  f := y(x) = _C1*exp(-x)

Then I noticed I needed to change "end proc();" to "end proc;"

The question is, why did Maple not generate a syntax error? If "end proc();" is valid Maple code, then what does it mean? or Did Maple ignore it? what is the parsing steps used to make Maple generate the above output?

## Simple program does not work...

I have two sets

f:={1,2,3,4};

h:={1,2,4,5}

L=seq(i,i=1..4):

I want to program , if it is true that f[i] = h[i], then it prints f[i]. So the output should be {1,2}.

for i in L do
if evalb(f[i]=h[i]) then
print(f[i]);
end if;
end do;

I get no output. https://i.imgur.com/qA5hU3i.png

I tried changing the set f to list, f:= [1,2,3,4], still no output.

## How to solve this PDE system?...

bbb2.mw

 (1)

 (2)

 (3)

 (4)

 (5)

if former equations are not solvable , please help me for another way, in which at first two equation solve..in this way in equation [J and B] assume that q[311]=e[311]=0 and dsolve perform to find Φ and  ψ

after by finding Φ and  ψ is use for detemine w and u0

bbb2_2.mw

## Long Commands in Maple...

hi all,

How could I write long commands in Maple?

For instance: a long vector in Matlab could be written in this way:

A=[ 3, 4, 5, 6, 6, 45, 37...

5, 4, 67, 39, -967 ];

But what is that in Maple???

## Incorrect syntax...

Error, illegal use of an object as a name''

thanks

PLATE.mw

## Can't assign values from a procedure...

I defined a procedure, OrderB(0,b,c), that essentially determines the order of a group that is defined by 2 parameters (the first parameter is always zero), so the output is an integer and the procedure is defined for every integer value of both parameters. I wanted to structure the outputs into a matrix with columns that represent one parameter and rows that represent the other. However, whenever I try to apply a method of defining the matrix, Maple returns the values of the procedure and then gives me an empty matrix.

>f:=proc (i, j) -> OrderB(0, i, j+3);
>Matrix(3, f);
1
4
1
1
4
1
1
4
1
[NULL,NULL...]

I tried a second method where I defined a set s such that:

s:={(0,0)=OrderB(0,0,0) , (0,1)=OrderB(0,0,1).....}

but upon execution, maple returns:

1
4
1
....
s:={(0,0)=( ), (0,1)=( )...}

Please Help. I don't know what I'm mising in the code that is keeping Maple from putting the outputs of my procedure into the matrix.

## Why does Maple 2016.1 improperly treat x^2?...

When experimenting with Maple 2016.1, I found several issues. One I have seen on MaplePrimes before (regarding "Error, incorrect syntax in parse: `;` unexpected (near 4th character of parsed string)" when evaluating an integral, for example, or trying to plot something), but another I have not seen - it may be related to the previous issue. Below is a document that contains some of the various errors I found. What is going on? It evaluates certain things correctly, but, in the integral, it treats "x^2" like a whole new variable (the integral of x^2 with respect to x from 0 to 2 it says is 2x^2, not 8/3). The same thing results in trying to plot x^2 (not shown), giving the same error if I were to say something like "plot(t,x=0..2)" - it cannot determine the plotting variable.

Any ideas? Are the two things (the Error, incorrect syntax in parse: `;` unexpected (near 4th character of parsed string) message and the bad integral value) related?

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