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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>])

f:2*r*sin(%pi/r)/sqrt(((1+r^2)+(1-r^2)*cos(2*%pi/r-2*phi))*((1+r^2)+(1-r^2)*cos(4*%pi/r-2*phi)));
plot3d(at(f,r=1/rI),[rI,1/4,3],[phi,-%pi,%pi],[grid,110,30]);

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-plot3d
plot3d(y - 3*(x - 1) - 1,[x,0,5],[y,0,8]);

f(x,y):= y - x^3;

...

x1:1;

Calculate

at-matrix

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

mat^(-1);

Calculate

at-denom-divide-num-scanmap

eq1: z*(a*b+a*a*b*b);

eq2: at(eq1,[z= -Q*(a...

eq3: scanmap(factor,n...

Calculate

at

at (x*y_p - (x_p - t_...

at (x*y_p - (x_p - t_...

Calculate

at-rat

rat(((9*(x+1)^2+6*(x+...

Calculate

at-block-mod-numer-rat-ratprint

rat(0.1234);

rat(0.12345);

rat(0.12345);

Calculate

at-block-equal-limit-makelist-plot2d
plot2d((x+1)/(x-1), [x, -10, 10], [y, -100, 100], [gnuplot_preamble, "set xtics 1"]);

continuous_at(expr, v...

continuous_at((x+1)/(...

plot2d((x+1)/(x-1), [...

Calculate

at-diff-linsolve-pi-plot2d-subst
plot2d(f2,[s,0,1]);

sd: 0.6;

f: s^2*(a0 + a1*s + a...

c0: at(f,s=1)=%pi;

Calculate

at-diff

f:x^2+3;

at(f,x=1);

diff(f,x);

Calculate

at-diff-divide-gcd

a^2=3;

P:4*X^4+2^(7/2)*a*X^3...

P1:diff(P,X);

Calculate