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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:5*4.57+3;
at(f,x=4,57);
df:diff(f,x);
at(df,x=4.57);
plot2d(df,[x,0,1])

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-cos-diff-linsolve-quad_qags-subst

f: a0 + a1*s^2 + a2*s^6;

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

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

Calculate

at-pred-rat

rat((x^2-1)/(x-1))=x+...

Calculate

at-phi-pi

pi:3.141592654;

d:2.50;

v:0.25;

Calculate

at-rat

rat((x^4-x^3-11*x^2+9...

rat((2-x)/(x+1))*((3*...

rat((x^3+2*x^2+4*x+8)...

Calculate

at-cos-integrate

at(.16*(integrate((3 ...

Calculate

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

f(x,y):= y^2 - x;

...

x1:2;

Calculate

at-diff

diff(v*e^(-at), e);

Calculate

at-diff-exp

p0(s)=s**4+2*s**2+2;

p1(s)=2*exp(-t*s);

p2(s)=exp(-2*t*s);

Calculate

at-rat

rat((x^4-x^3-11*x^2+9...

rat((2-x)/(x+1))*(3*x...

rat((x^3+2*x^2+4*x+8)...

Calculate