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subsop

substitute for specified operands in an expression

 

Calling Sequence

Parameters

Description

Thread Safety

Examples

An example involving integrals

Calling Sequence

subsop(eq1, eq2, ..., eqn, expr)

Parameters

eq[i]

-

(optional) equation of the form speci=expri, where each speci is an integer or list of integers, and each expri is an expression

expr

-

expression

Description

• 

The subsop function is used to replace specified operands of an expression with new values. It will do the simultaneous substitutions specified by the eqi equation arguments in the last argument expr. The result is obtained by replacing op(spec1, expr) by expr1, op(spec2, expr) by expr2, ..., and op(specn, expr) by exprn in expr.

• 

Each speci can be either an integer, or a list of integers. If a list of integers is specified, the integers refer to sub-operands of expr at increasing nesting levels. See op for further details.

• 

The integer(s) comprising each speci must lie in the range nopsexpr..nopsexpr.  A speci of 0 is allowed only for function, indexed expression, and series exprs.

• 

If an integer n in a speci is negative, it is considered equivalent to nopsexpr+n+1.

• 

If no eqi are specified, subsop returns its argument with no substitutions.

• 

See also the applyop command which can be used to apply a function to specified operands of an expression.

• 

The action of substitution is not followed by evaluation. In cases where full evaluation is desired, the eval command should be used.

Thread Safety

• 

The subsop command is thread-safe as of Maple 15.

• 

For more information on thread safety, see index/threadsafe.

Examples

px7+8x6+x29

p:=x7+8x6+x29

(1)

op2,p

8x6

(2)

subsop2=y,p

x7+x2+y9

(3)

subsop2=op2,p,p

x78x6+x29

(4)

subsop1=0,p

8x6+x29

(5)

subsop1=1,xyz

yz

(6)

subsop1=NULL,2=z,3=y,x,y,z

z,y

(7)

subsop0=g,fa,b,c

ga,b,c

(8)

pfx,gx,y,z,x

p:=fx,gx,y,z,x

(9)

subsop2,3=w,p

fx,gx,y,w,x

(10)

subsop2,0=h,2,3=w,3=a,p

fx,hx,y,w,a

(11)

subsopp

fx,gx,y,z,x

(12)

An example involving integrals

  

You can use subsop and applyop to perform a change of variables in an integral step-by-step.

Int(sin(sqrt(x)),x=0..t);

∫0tsinxⅆx

(13)
  

Apply the change of variable u = x^(1/2)

subsop( [1,1]=u, (13) );

∫0tsinuⅆx

(14)
  

We have dx = 2*u*du

subsop( 1=2*u*op(1,(14)), [2,1]=u, (14) );

∫0t2usinuⅆu

(15)

applyop( sqrt, [2,2,2], (15) );

∫0t2usinuⅆu

(16)

See Also

applyop

eval

membertype

op

subs

 


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