slepc-3.21.2 2024-09-25
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# FNSetScale

Sets the scaling parameters that define the matematical function.

### Synopsis

    #include "slepcfn.h"
    PetscErrorCode FNSetScale(FN fn,PetscScalar alpha,PetscScalar beta)

Logically Collective

### Input Parameters

| fn | - the math function context
| alpha | - inner scaling (argument)
| beta | - outer scaling (result)

### Notes

Given a function f(x) specified by the FN type, the scaling parameters can be used to realize the function beta*f(alpha*x). So when these values are given, the procedure for function evaluation will first multiply the argument by alpha, then evaluate the function itself, and finally scale the result by beta. Likewise, these values are also considered when evaluating the derivative.

If you want to provide only one of the two scaling factors, set the other one to 1.0.

### See Also

FNGetScale(), FNEvaluateFunction()

### Level

intermediate

### Location

src/sys/classes/fn/interface/fnbasic.c

### Examples

src/eps/tutorials/ex36.c
src/mfn/tutorials/ex23.c
src/mfn/tutorials/ex23f.F90
src/mfn/tutorials/ex37.c
src/mfn/tutorials/ex39.c
src/nep/tutorials/ex22.c
src/nep/tutorials/ex22f.F90
src/nep/tutorials/nlevp/gun.c
Index of all FN routines
Table of Contents for all manual pages
Index of all manual pages