Reference Guide

3-228 Full Command and Function Reference
When plot type is set to SLOPEFIELD, the DRAW command plots a slope representation of a
scalar function with two variables. SLOPEFIELD requires values in the reserved variables EQ,
VPAR, and PPAR.
VPAR has the following form:
{ x
left
x
right
y
near
y
far
z
low
z
high
x
min
x
max
y
min
y
max
x
eye
y
eye
z
eye
x
step
y
step
}
For plot type SLOPEFIELD, the elements of VPAR are used as follows:
• x
left
and x
right
are real numbers that specify the width of the view space.
• y
near
and y
far
are real numbers that specify the depth of the view space.
• z
low
and z
high
are real numbers that specify the height of the view space.
• x
min
and x
max
are not used.
• y
min
and y
max
are not used.
• x
eye
, y
eye
, and z
eye
are real numbers that specify the point in space from which the graph is
viewed.
• x
step
and y
step
are real numbers that set the number of x-coordinates versus the number of y-
coordinates plotted.
The plotting parameters are specified in the reserved variable PPAR, which has this form:
{ (x
min
, y
min
) (x
max
, y
max
) indep res axes ptype depend }
For plot type SLOPEFIELD, the elements of PPAR are used as follows:
• (x
min
, y
min
) is not used.
• (x
max
, y
max
) is not used.
• indep is a name specifying the independent variable. The default value of indep is X.
• res is not used.
• axes is not used.
• ptype is a command name specifying the plot type. Executing the command SLOPEFIELD
places the command name SLOPEFIELD in ptype.
• depend is a name specifying the dependent variable. The default value is Y.
Access: …µ SLOPEFIELD
Input/Output: None
See also: BAR, CONIC, DIFFEQ, FUNCTION, GRIDMAP, HISTOGRAM, PARAMETRIC,
PARSURFACE, PCONTOUR, POLAR, SCATTER, TRUTH, WIREFRAME, YSLICE
SNEG
Type: Command
Description: Store Negate Command: Replaces the contents of a variable with its negative.
The named object must be a number, an array, an algebraic object, a unit object, or a graphics
object. For information on negation, see NEG.
Access: !° MEMORY ARITHMETIC L SNEG ( °is the left-shift of the Nkey).
Input/Output:
Level 1/Argument 1 Level 1/Item 1
'name'
→
See also: NEG, SCONJ, SINV
SNRM
Type: Command
Description: Spectral Norm Command: Returns the spectral norm of an array.
The spectral norm of a vector is its Euclidean length, and is equal to the largest singular value of a
matrix.
Access: !Ø OPERATIONS L L SNRM ( Ø is the left-shift of the 5key).
!´ MATRIX NORMALIZE SNRM ( ´ is the left-shift of the Pkey).