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scale Reference

Map values to an output range

scale

Description

The scale object maps an input range of float or integer values to an output range. The output range can be larger or smaller than the input range, can be inverted and can change numeric type. If specified, the mapping can also be exponential.

Examples

An example of how to scale an integer slider into a useful range of floating-point values

Arguments

input-low [number]

Optional

Sets the low end of the expected input range. Incoming values are not clipped to this range; rather, the input range is used to determine the value mapping formula.

input-high [number]

Optional

Sets the high end of the expected input range. Incoming values are not clipped to this range; rather, the input range is used to determine the value mapping formula.

output-low [number]

Optional

This sets the low end of the output range, and will be the lowest output value if the input value stays with its expected range.

output-high [number]

Optional

This sets the high end of the output range, and will be the highest output value if the input value stays with its expected range.

exponential [float]

Optional

This optional fifth argument specifies the nature of the scaling curve. This argument must be a floating-point number greater than 1., with larger values leading to steeper exponential curves.

In classic mode a typical value for this argument is 1.06. The object does its actual scaling after the exponential calculation, and the number is converted according to the following expression:
(out_high-out_low >= 0) ? (out_low + (out_high-out_low) * ( (out_high - out_low) * exp(-1*(in_high-in_low)*log(power)) * exp(x*log(power)) )) : (-1) * ( out_low + (out_high-out_low) * ( (out_high - out_low) * exp(-1*(in_high-in_low)*log(power)) * exp(x*log(power)) ) )

In non- classic (modern) mode the value for the scaling curve must be higher than 0. and is converted according to the following expression:

((x-in_low)/(in_high-in_low) == 0) ? out_low : (((x-in_low)/(in_high-in_low)) > 0) ? (out_low + (out_high-out_low) * ((x-in_low)/(in_high-in_low))^exp) : ( out_low + (out_high-out_low) * -((((-x+in_low)/(in_high-in_low)))^(exp)))

Note that prior to Max 6.0.4 the exponent was inverted. Thus, if you gave it an exponent of 2 the object behaved like it had an exponent of 0.5, and if you gave it an exponent of 0.5 it behaved like it had an exponent of 2. Patches from versions prior to 6.0.4 may require updating to work properly.

Attributes

classic [int]

Classic mode uses exponential function that is backward compatible with old IRCAM patchers.

Common Box Attributes

Messages

bang

Perform the scaling operation on the most recently received input value. If the range values have been changed, the scaling will be based on the new range.

int

Arguments

input [int]
The scaling function is performed on the incoming value. If any of the range types are floating point, the value is converted into a float for the calculation.

float

Arguments

input [float]
In left inlet: The scaling function is performed on the incoming value. If the input range type is integer, the value is converted into an int for the calculation.

In second inlet: Sets the low end of the input range.

In third inlet: Sets the high end of the input range.

In fourth inlet: Sets the low end of the output range.

In fifth inlet: Sets the high end of the output range.

In sixth inlet: Sets the scaling curve value as described in the object arguments section.

list

Arguments

input [list]
A list of numbers sent to the left inlet will trigger the output of a list with the results of scaling operation perforned on each item.

Output

float

When scale receives a value in its leftmost inlet, that value is scaled to the indicated output range of values.

int

If only four arguments are provided and all four are of type int, scale will output scaled values as integers. Otherwise output is floating-point.

See Also

Name Description
expr
linedrive
zmap
Max Basic Tutorial 11: Procedural Drawing Max Basic Tutorial 11: Procedural Drawing