Items tagged with conditional



While running a maple code, I am getting a "invalid if statement termination" error. Most of time when I use nested for loop and if statement inside the loop, I am getting this error. Another error I get frequently is "Error, unterminate loop". I am using "shift+Enter" instead of Enter to avoid blanks but still such error appears. Can any one provide some rules which I should keep in mind to avoid these errors. My maple worksheet is enclosed-

Thanks and Regards,


I really want to use if condition inside of eval and sum, example as below:

sum(eval(y=x^(j),(if j=1 then x=2 else x=3 fi)),j=1..2)

The reason is: the value of x to be evaluated depends on the value of j which differs inside of the sum (in the context of B-spline functions).

Any lights? Thanks,

I have a function which calculates a number for [x,y] inside a matrix, which depends on the values surrounding said initial cell (from [x-1,y-1] yo [x+1,y+1]). However, for the values on the border, the idea is to go around to the opposite side, creating a Torus of the sort.
The solution I seemed to have found was to create 4 indices: 2 controled with 'for' and 2 which were modified accordingly to be used as imputs for the function:

for r from x-1 to x+1 do
    for t from y-1 to y+1 do
        if r=0 then i:=N; else i:=r; fi;
        if t=0 then j:=N; else j:=t; fi;
        if r=N+1 then i:=1; else i:=r; fi;
        if t=N+1 then j:=1; else j:=t; fi;
od; od;

(the print commands are for the tests I have been running so see where the potential error lied).
If you run this script, you can clearly see for x0,y0<>1 that it works perfectly, even for x0,y0=N where it succesfully goes around and changes to 1. However, for x0,y0=1 it isn't able to detect that r&t=0 and so it doesn't change it to N; creating an error where it tries to find the value 0 of an Array.

Thanks in advance,

I have attached the problem here. I need to say sorry, because I did not provide the whole code. So, automatically It will be error if you execute it.

If you see the attachement, you will see "Result_Eva_GB_X2[3] := []". It makes a problem if I want to make comparison. So I want the result of "Result_Eva_GB_X2[3] := []" is [0].

Actually the result of Result_Eva_GB_X2[3] := [] is complex number, because I did not want the complex I made select(x->is(0<x<1)....) to eliminate the complex number and negative result. So the question is How do I make the result of Result_Eva_GB_X2[3] := [] is [0]?

I have tried to add "Selection Statement (if)" (If the result is Undefined ([]) then Result_Eva_GB_X2[3] := [0]) But it can not work. Or maybe the selection statement that I made was wrong.

Please Help me. Thank You very much

restart; with(LinearAlgebra); with(Student[LinearAlgebra]); 
Z := Matrix([[3, 1, 5, 4, 5], [0, 0, 0, 0, 0], [28, 6, 4, 5, 9], [98, 5, 82, 2, 4], [24, 55, 23, 22, 90]]); 
B := Matrix([[0], [0], [0], [0], [0]]); 
A := <Z|B>:
if Row(A, 2) = ZeroVector[row](6) then A; end if;

I used the code above but it didn't work...any help appreciated

When I write an conditional command I come back and press enter again and again but I need only last one for example 




>if f(x) <g(x) then;

>x:=x+1 elif f(x) >g(x) then;

>y:=y+1 elif f(x)=g(x) then;



>f(x) end if;

I push enter and it write x:=1 then I click if command and push enter again and it writes x:=2 and continues like y:=1, x:=3, y:=2, x:=4,  y:=3 and lastly 




But I only need last one. Can I do this only push enter once. Of course my problem is more complicated than this f(x) , g(x) . Thanks



I have the following question:

Illustrate how the sequence N->R de fined by n ->n^2/n^2 + 31n + 228 can be shown to be
within a given epsilon > 0 of its limiting value x0.
(a) use an appropriate conditional statement to find N such that abs (xn -􀀀 x0) < epsilon for every n>=N
and produce an appropriate list of the data points (n,xn) to illustrate

I found N but without using any CONDITIONAL STATEMENT.Can you help me find N using IF FOR WHILE?

i am trying to execute the following code but i am having the following error:

A:=Matrix(21,4):A(1,2):=0:A(2,2):=0:t:=2: thetasec:=-8.724679300*10^(20):  for z from 0.1 by 0.05 to 1 do  t:=t+1: A[t,1]:=z:  x:=2*A[t-1,2]-A[t-2,2]+thetasec*0.05^(2):  theta2:=evalf(arctan(sin(x-Pi),cos(x-Pi))+Pi):    if theta2>Pi/(2)and theta2<=(3*Pi)/(2)then   A[t,2]:=theta2-Pi   elif theta2>(3*Pi)/(2)then A[t,2]:=theta2-2*Pi else  A[t,2]:=theta2 fi:  A[t,3]:=cos(A[t,2]):  A[t,4]:=sin(A[t,2]):

A:=Matrix(21,4):A(1,2):=0:A(2,2):=0:t:=2: thetasec:=-8.724679300*10^(20):  for z from 0.1 by 0.05 to 1 do  t:=t+1: A[t,1]:=z:  x:=2*A[t-1,2]-A[t-2,2]+thetasec*0.05^(2):  theta2:=evalf(arctan(sin(x-Pi),cos(x-Pi))+Pi):    if theta2>Pi/(2)and theta2<=(3*Pi)/(2)then   A[t,2]:=theta2-Pi   elif theta2>(3*Pi)/(2)then A[t,2]:=theta2-2*Pi else  A[t,2]:=theta2 fi:  A[t,3]:=cos(A[t,2]):  A[t,4]:=sin(A[t,2]):od

Error, cannot determine if this expression is true or false: (1/2)*Pi < 3.535344555 and 3.535344555 <= (3/2)*Pi

what is causing this error and how can i fix it 


i have a conditional expression like this 

for i from ... do

if .... then



end if;


i face this error during caculation:
Error, reserved word `else` unexpected

what should i do?

Hi everyone, I'm new to the forum and also new to Maple.


I am trying to do the following:

"Write a procedure, marks, to take a student’s mark and output the appropriate grade, based on the following table:"


0   – 39.99

I just found out something which I don't understand.

Why am I getting this answer?

solve(a*x = 0, {x});
                                   {x = 0}


When I try some similar expressions I see it behaves differently for equality and inequality.

solve(a*x <= 0, {x});...

Hi Guys, I hope you can help!

I am stuck trying to plot a function that has a conditional based on 'x' the plotted variable.


> pltx := proc (num1::integer, num2::integer, x) 
if 1 < x then
return 0
elif x < 0 then
return 0
return num1*x^num2
end if
end proc;

> d := plot(pltx(2, 5, x), x = 0.1 .. 0.4);

Error, (in pltx) cannot determine if this expression is true or false: 1 < x

Hello and thank you in advance,

I am used to Mathematica and am looking to switch, conditionals in Mathematica seem easy, like say


  If[0 < z && -6 <= y <= 6 && 0 < x < 1             ,Null             ,Return[0]];


How do you replicate this in an easy to read way without lots of nested if statements?

Hello, I'm Tam and I had a problem with Conditional of Jacobi Iteration.

So, the proplem is:




And I want to check the condition

with the maple program.

Fisrt, I typed

b:=sum(abs('A'[1,j]),j=1..ColumnDimension(A)); and I got b:=7


I meet a problem. When I use command "if" in command "for", there is nothing.I don't know reason. Can anyone tell me the reason?

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