Assigning value Conditional statement Loops Examples

Computer Algebra SystemsFundamentals of Programming

Sándor Czirbuszczirbusz@gmail.com

http://compalg.inf.elte.hu/~czirbusz/

Department of Computer AlgebraInformatics Institute, ELTE

D2.711A

2011-2012 spring

http://compalg.inf.elte.hu/~czirbusz/

Assigning value Conditional statement Loops Examples

Index

1 Assigning valueIn MapleIn Sage

2 Conditional statementThe IF in MapleThe IF in Sage

3 LoopsIn Maple

The for/from loopThe for/in loopThe while loop

General loopsLoops in Sage

4 Examples

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);

Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)

Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’

unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)

evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.

parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.parameters in form “a,b”: a = b (for simple variables)

parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Maple

In Maple

name := expr;(name1, ..., namen) := (expr1, ..., exprn);Test it: assigned(name)Undoing it:

name:=’name’unassign(’name1’,’name2’,...)evaln( name );

The statement assign:assign(a,b), assign(A=B), assign(L) :

it evaluates both sides.parameters in form “a,b”: a = b (for simple variables)parameters in form “A,B”: A,B expression sequences withsame length

Assigning value Conditional statement Loops Examples

In Sage

in Sage

Exept the variable “x” the [varlist =] var(’[varlist]’)declaration is compulsory. If the variables exist, then themvalue is deleted.

Assigning value: var = expressIn the same manner: var1, var2, . . . = kif1, kif2 ,. . . .If there is one variable and on the right side there areseveral expression, then the type of variables “tuple”.

Assigning value Conditional statement Loops Examples

In Sage

in Sage

Exept the variable “x” the [varlist =] var(’[varlist]’)declaration is compulsory. If the variables exist, then themvalue is deleted.Assigning value: var = express

In the same manner: var1, var2, . . . = kif1, kif2 ,. . . .If there is one variable and on the right side there areseveral expression, then the type of variables “tuple”.

Assigning value Conditional statement Loops Examples

In Sage

in Sage

Exept the variable “x” the [varlist =] var(’[varlist]’)declaration is compulsory. If the variables exist, then themvalue is deleted.Assigning value: var = expressIn the same manner: var1, var2, . . . = kif1, kif2 ,. . . .

If there is one variable and on the right side there areseveral expression, then the type of variables “tuple”.

Assigning value Conditional statement Loops Examples

In Sage

in Sage

Exept the variable “x” the [varlist =] var(’[varlist]’)declaration is compulsory. If the variables exist, then themvalue is deleted.Assigning value: var = expressIn the same manner: var1, var2, . . . = kif1, kif2 ,. . . .If there is one variable and on the right side there areseveral expression, then the type of variables “tuple”.

Assigning value Conditional statement Loops Examples

The IF in Maple

Conditional statement I

if cond1 thenstatement_sequ1

elif cond2 thenstatement_sequ2

elif cond3 thenstatement_sequ3............

elsestatement_sequN

end if

Assigning value Conditional statement Loops Examples

The IF in Maple

Conditional statement II

Constructing and evaluating conditional statements:

Relations: ,

Logical operators: and, or, xor, implies, not

Logical constants: true, false, FAIL

Boolean evaluation: evalb, testeq, or is

Remark: The logic in Maple interpreter is a trivalent logic.

Assigning value Conditional statement Loops Examples

The IF in Sage

Conditional statement

if cond1:statement_sequ1

elif cond2:statement_sequ2

elif cond3:statement_sequ3............

else:statement_sequN

There are not end of block statement; teh colon is compulsory.

Assigning value Conditional statement Loops Examples

The IF in Sage

Constructing conditional statements

Testing : expr1 == expr2 or kif1 is kif2

Logical operators: and, or, notThe logical evaluation is more natural the in maple.

Assigning value Conditional statement Loops Examples

The IF in Sage

Constructing conditional statements

Testing : expr1 == expr2 or kif1 is kif2Logical operators: and, or, not

The logical evaluation is more natural the in maple.

Assigning value Conditional statement Loops Examples

The IF in Sage

Constructing conditional statements

Testing : expr1 == expr2 or kif1 is kif2Logical operators: and, or, notThe logical evaluation is more natural the in maple.

Assigning value Conditional statement Loops Examples

In Maple

The for/from loop

for counter from init by increment to final dostatement_seq

end do

The clauses from, by and to are optional, they are in arbitraryorder. Default values: by =1, from = 0.

Assigning value Conditional statement Loops Examples

In Maple

The for/in loop

for variable in expr dostatement_seq

end do

The value of variable runs through all value of the compoundstructure "expr" and executed every time. Such is in PHP theloop foreach.

Assigning value Conditional statement Loops Examples

In Maple

The while loop

while condition dostatement_seq

end do

Assigning value Conditional statement Loops Examples

General loops

General loops

for counter from initial by increment to finalwhile condition dostatement_seqend do

for variable in expression while condition dostatement_seq

end do

Influencing the run of loop: break,next

Assigning value Conditional statement Loops Examples

Loops in Sage

The FOR iteration I

for counter in range():statement_seq

The parameters of range are the usual start value(the default is0), end value and the step (default = 1).Differently from other languages the loop does not run on theend value.Variants:

range : it makes a listxrange : it is an iterator, not a list, therefore it is faster.srange : it is the slower (there are other parameters), it

makes a list too.

Assigning value Conditional statement Loops Examples

Loops in Sage

The FOR iteration I

for counter in obj:statement_seq

here the “obj” is a compound object, mostly a list. The colon iscompulsory here; the body of loop continues until the end ofindentation.

Assigning value Conditional statement Loops Examples

Loops in Sage

The while loop

wile logical_cond:statement_seq

It is the usual while of Python.

Assigning value Conditional statement Loops Examples

Examples

In practice.

Assigning valueIn MapleIn Sage

Conditional statementThe IF in MapleThe IF in Sage

LoopsIn MapleGeneral loopsLoops in Sage

Examples