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The Maxima on-line user's manual

Algebra Calculator

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At Calculator

At

Function: at (<expr>, [<eqn_1>, ..., <eqn_n>])

rat((x^4-x^3-11*x^2+9*x+18)/(x^4-3*x^3-7*x^2+27*x-18))/((x^3-9*x^2+26*x-24)/(x^3-8*x^2+19*x-12));
rat((2-x)/(x+1))*(3*x^4-24*x^3-3*x^2+204*x-252)/(220*x-70*x^2-168-15*x^3+10*x^4-x^5);
rat((x^3+2*x^2+4*x+8)/(x^5+5*x^4-16*x-80))*(2*x^4+10*x^3-16*x-80)/(x^2+2*x+4);
rat((2*x^4+10*x^3-2*x-10)/(x^2+x+1))*(x^3+x^2+x+1)/(x^5+5*x^4-x-5);
rat((4*x^4+x^5-81*x-324)/(3*x^4+10*x^3-81*x-270))*(3*x^3+19*x^2+57*x+90)/(x^4+7*x^3+21*x^2+63*x+108);
rat((4*x^5+40*x^4+100*x^3-80*x^2-320*x+256)/(x^4+x^3-9*x^2+11*x-4))*(3*x^3-3*x^2)/(x^2+8*x+16);

Function: at (<expr>, <eqn>) Evaluates the expression <expr> with the variables assuming the values as specified for them in the list of equations [<eqn_1>, ..., <eqn_n>] or the single equation <eqn>.

If a subexpression depends on any of the variables for which a value is specified but there is no atvalue specified and it cant be otherwise evaluated, then a noun form of the at is returned which displays in a two-dimensional form.

at carries out multiple substitutions in series, not parallel.

See also atvalue. For other functions which carry out substitutions, see also subst and ev.

Examples:

          (%i1) atvalue (f(x,y), [x = 0, y = 1], a^2);
                                          2
          (%o1)                          a
          (%i2) atvalue (diff (f(x,y), x), x = 0, 1 + y);
          (%o2)                        @2 + 1
          (%i3) printprops (all, atvalue);
                                          !
                            d             !
                           --- (f(@1, @2))!       = @2 + 1
                           d@1            !
                                          !@1 = 0

2 f(0, 1) = a

          (%o3)                         done
          (%i4) diff (4*f(x, y)^2 - u(x, y)^2, x);
                            d                          d
          (%o4)  8 f(x, y) (-- (f(x, y))) - 2 u(x, y) (-- (u(x, y)))
                            dx                         dx
          (%i5) at (%, [x = 0, y = 1]);
                                                   !
                        2              d           !
          (%o5)     16 a  - 2 u(0, 1) (-- (u(x, y))!            )
                                       dx          !
                                                   !x = 0, y = 1

There are also some inexact matches for at. Try ?? at to see them.

(%o1)                                true
(%i2) 

At Example

Related Examples

at-diff-linsolve-quad_qags-subst

f:a0+a1*s^2+a2*s^4;

cond1:at(f,s=1)=0;

cond2:at(diff(f,s),s=...

Calculate

at-cos-diff-linsolve-plot2d-quad_qags-subst
plot2d(zer1,[t,0.0,1]);

f: a0 + a1*s^2 + a2*s...

cond1: at(f,s=1)=0;

cond2: at(diff(f,s),s...

Calculate

at-rectform

at ((1/(c*(x+%i*y) + ...

(1/(c*(x+%i*y) + d)^4...

Calculate

at-diff-ratsimp

sn(f,x,g):=g-at(f,x=g...

ratsimp(sn(x^2-a,x,sn...

%,a=3,g=2;

Calculate

at-rectform

at ((1/(c*(x+%i*y) + ...

Calculate

at-solve

z: V1*p1/T1 = V2*p2/T2;

isop: z, p1=1, p2=1;

isoV: z, V1=1, V2=1;

Calculate

at-laplace-sin-solve

inv_laplace(sin(at),t...

solve(%o1);

Calculate

at-matrix

mat:matrix([1,2,3],[2...

mat[2,2]: a;

Calculate

at-diff-plot2d-sin
plot2d(df,[x,0,1]);

f:sin(x)^2+3;

at(f,x=1);

df:diff(f,x);

Calculate

at-determinant-matrix-sqrt

mat : 1/3*matrix( [ (...

determinant(mat);

Calculate